A new fibrin sealant as a three-dimensional scaffold candidate for mesenchymal stem cells

Towards Stem Cell Therapy for Critical-Sized Segmental Bone Defects: Current Trends and Challenges on the Path to Clinical Translation

The management and reconstruction of critical-sized segmental bone defects remain a major clinical challenge for orthopaedic clinicians and surgeons. In particular, regenerative medicine approaches that involve incorporating stem cells within tissue engineering scaffolds have great promise for fracture management. This narrative review focuses on the primary components of bone tissue engineering-stem cells, scaffolds, the microenvironment, and vascularisation-addressing current advances and translational and regulatory challenges in the current landscape of stem cell therapy for critical-sized bone defects. To comprehensively explore this research area and offer insights for future treatment options in orthopaedic surgery, we have examined the latest developments and advancements in bone tissue engineering, focusing on those of clinical relevance in recent years. Finally, we present a forward-looking perspective on using stem cells in bone tissue engineering for critical-sized segmental bone defects.

Heterologous fibrin biopolymer as an emerging approach to peripheral nerve repair: a scoping review

Nerve injuries present a substantial challenge within the medical domain due to their prevalent occurrence and significant impact. In nerve injuries, a range of physiopathological and metabolic responses come into play to stabilize and repair the resulting damage. A critical concern arises from the disruption of connections at neuromuscular junctions, leading to profound degeneration and substantial loss of muscle function, thereby hampering motor tasks. While end-to-end neurorrhaphy serves as the established technique for treating peripheral nerve injuries, achieving comprehensive morphofunctional recovery remains a formidable challenge. In pursuit of enhancing the repair process, alternative and supportive methods are being explored. A promising candidate is the utilization of heterologous fibrin biopolymer, a sealant devoid of human blood components. Notably, this biopolymer has showcased its prowess in establishing a stable and protective microenvironment at the site of use in multiple scenarios of regenerative medicine. Hence, this scoping review is directed towards assessing the effects of associating heterologous fibrin biopolymer with neurorrhaphy to treat nerve injuries, drawing upon findings from prior studies disseminated through PubMed/MEDLINE, Scopus, and Web of Science databases. Further discourse delves into the intricacies of the biology of neuromuscular junctions, nerve injury pathophysiology, and the broader utilization of fibrin sealants in conjunction with sutures for nerve reconstruction procedures. The association of the heterologous fibrin biopolymer with neurorrhaphy emerges as a potential avenue for surmounting the limitations associated with traditional sealants while also mitigating degeneration in nerves, muscles, and NMJs post-injury, thereby fostering a more conducive environment for subsequent regeneration. Indeed, queries arise regarding the long-term regenerative potential of this approach and its applicability in reconstructive surgeries for human nerve injuries.

Enhancing differentiation of menstrual blood-derived stem cells into female germ cells using a bilayer amniotic membrane and nano-fibrous fibroin scaffold

Three-dimensional nanofiber scaffolds offer a promising method for simulating in vivo conditions within the laboratory. This study aims to investigate the influence of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold on the differentiation of human menstrual blood mesenchymal stromal/stem cells (MenSCs) into female germ cells. MenSCs were isolated and assigned to four culture groups: (i) MenSCs co-cultured with granulosa cells (GCs) using the scaffold (3D-T group), (ii) MenSCs using the scaffold alone (3D-C group), (iii) MenSCs co-cultured only with GCs (2D-T group), and (iv) MenSCs without co-culture or scaffold (2D-C group). Both MenSCs and GCs were independently cultured for two weeks before co-culturing was initiated. Flow cytometry was employed to characterize MenSCs based on positive markers (CD73, CD90, and CD105) and negative markers (CD45 and CD133). Additionally, flow cytometry and immunocytochemistry were used to characterize the GCs. Differentiated MenSCs were analyzed using real-time PCR and immunostaining. The real-time PCR results demonstrated significantly higher levels of VASA expression in the 3D-T group compared to the 3D-C, 2D-T, and 2D-C groups. Similarly, the SCP3 mRNA level in the 3D-T group was notably elevated compared to the 3D-C, 2D-T, and 2D-C groups. Moreover, the expression of GDF9 was significantly higher in the 3D-T group when compared to the 3D-C, 2D-T, and 2D-C groups. Immunostaining results revealed a lack of signal for VASA, SCP3, or GDF9 markers in the 2D-T group, while some cells in the 3D-T group exhibited positive staining for all these proteins. These findings suggest that the combination of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold with co-culturing GCs facilitates the differentiation of MenSCs into female germ cells.

Ultrastructural Evidence of Synapse Preservation and Axonal Regeneration Following Spinal Root Repair with Fibrin Biopolymer and Therapy with Dimethyl Fumarate

Spinal cord injury causes critical loss in motor and sensory function. Ventral root avulsion is an experimental model in which there is the tearing of the ventral (motor) roots from the surface of the spinal cord, resulting in several morphological changes, including motoneuron degeneration and local spinal cord circuitry rearrangements. Therefore, our goal was to test the combination of surgical repair of lesioned roots with a fibrin biopolymer and the pharmacological treatment with dimethyl fumarate, an immunomodulatory drug. Thus, adult female Lewis rats were subjected to unilateral ventral root avulsion of L4-L6 roots followed by repair with fibrin biopolymer and daily treatment with dimethyl fumarate (15 mg/Kg; gavage) for 4 weeks, the survival time post-surgery being 12 weeks; n = 5/group/technique. Treatments were evaluated by immunofluorescence and transmission electron microscopy, morphometry of the sciatic nerve, and motor function recovery. Our results indicate that the combination between fibrin biopolymer and dimethyl fumarate is neuroprotective since most of the synapses apposed to alfa motoneurons were preserved in clusters. Also, nerve sprouting occurred, and the restoration of the 'g' ratio and large axon diameter was achieved with the combined treatment. Such parameters were combined with up to 50% of gait recovery, observed by the walking track test. Altogether, our results indicate that combining root restoration with fibrin biopolymer and dimethyl fumarate administration can enhance motoneuron survival and regeneration after proximal lesions.

Human dental pulp stem cell monolayer and spheroid therapy after spinal motor root avulsion in adult rats

Spinal cord injuries result in severe neurological deficits and neuronal loss, with poor functional recovery. Mesenchymal stem cells have shown promising results; therefore the present objective of this work was to compare motor recovery after treatment with human dental pulp stem cells (hDPSC) cultivated in monolayer (2D) or as spheroids (3D), following avulsion and reimplantation of spinal motor roots in adult rats. Thus, 72 adult female Lewis rats were divided into 4 groups: avulsion (AV); avulsion followed by reimplantation (AR); avulsion associated with reimplant and 2D cell therapy (AR + 2D), and avulsion associated with reimplant and 3D cell therapy (AR + 3D). The application of the cells in 2D and 3D was performed by microsurgery, with subsequent functional assessment using a walking track test (Catwalk system), immunohistochemistry, neuronal survival, and qRT-PCR in 1-, 4-, and 12-weeks post-injury. The animals in the AR + 2D and AR + 3D groups showed the highest neuronal survival rates, and immunofluorescence revealed downregulation of GFAP, and Iba-1, with preservation of synaptophysin, indicating a reduction in glial reactivity, combined with the maintenance of pre-synaptic inputs. There was an increase in anti-inflammatory (IL-4, TGFβ) and a reduction of pro-inflammatory factors (IL-6, TNFα) in animals treated with reimplantation and hDPSC. As for the functional recovery, in all analyzed parameters, the AR + 2D group performed better and was superior to the avulsion alone. Overall, our results indicate that the 2D and 3D cell therapy approaches provide successful immunomodulation and motor recovery, consistent with advanced therapies after spinal cord injury.

Acetylcholine receptors of the neuromuscular junctions present normal distribution after peripheral nerve injury and repair through nerve guidance associated with fibrin biopolymer

Peripheral nerve injuries (PNI) lead to alterations in the Agrin-LRP4-MuSK pathway. This results in disaggregation of AChRs and change from epsilon (mature, innervated) to gamma (immature, denervated) subunit. Tubulization technique has been shown to be effective for PNI repair and it also allows the use of adjuvants, such as fibrin biopolymer (FB). This study evaluated the effect of the association of tubulization with FB after PNI on AChRs and associated proteins. Fifty-two adults male Wistar rats were used, distributed in 4 experimental groups: Sham Control (S), Denervated Control (D); Tubulization (TB) and Tubulization + Fibrin Biopolymer (TB+FB). Catwalk was performed every 15 days. Ninety days after surgery the right soleus muscles and ischiatic nerves were submitted to the following analyses: (a) morphological and morphometric analysis of AChRs by confocal microscopy; (b) morphological and morphometric analysis of the ischiatic nerve; (c) protein quantification of AChRs: alpha, gama, and epsilon, of Schwann cells, agrin, LRP4, MuSK, rapsyn, MMP3, MyoD, myogenin, MURF1 and atrogin-1. The main results were about the NMJs that in the TB+FB group presented morphological and morphometric approximation (compactness index; area of the AChRs and motor plate) to the S group. In addition, there were also an increase of S100 and AChRε protein expression and a decrease of MyoD. These positive association resulted in AChRs stabilization that potentiate the neuromuscular regeneration, which strengthens the use of TB for severe injuries repair and the beneficial effect of FB, along with tubulization technique.

Tissue Bioengineering with Fibrin Scaffolds and Deproteinized Bone Matrix Associated or Not with the Transoperative Laser Photobiomodulation Protocol

Extending the range of use of the heterologous fibrin biopolymer, this pre-clinical study showed a new proportionality of its components directed to the formation of scaffold with a lower density of the resulting mesh to facilitate the infiltration of bone cells, and combined with therapy by laser photobiomodulation, in order to accelerate the repair process and decrease the morphofunctional recovery time. Thus, a transoperative protocol of laser photobiomodulation (L) was evaluated in critical bone defects filled with deproteinized bovine bone particles (P) associated with heterologous fibrin biopolymer (HF). The groups were: BC_L (blood clot + laser); HF; HF_L; PHF (P+HF); PHF_L (P+HF+L). Microtomographically, bone volume (BV) at 14 days, was higher in the PHF and PHF_L groups (10.45 ± 3.31 mm³ and 9.94 ± 1.51 mm³), significantly increasing in the BC_L, HF_L and PHF_L groups. Histologically, in all experimental groups, the defects were not reestablished either in the external cortical bone or in the epidural, occurring only in partial bone repair. At 42 days, the bone area (BA) increased in all groups, being significantly higher in the laser-treated groups. The quantification of bone collagen fibers showed that the percentage of collagen fibers in the bone tissue was similar between the groups for each experimental period, but significantly higher at 42 days (35.71 ± 6.89%) compared to 14 days (18.94 ± 6.86%). It can be concluded that the results of the present study denote potential effects of laser radiation capable of inducing functional bone regeneration, through the synergistic combination of biomaterials and the new ratio of heterologous fibrin biopolymer components (1:1:1) was able to make the resulting fibrin mesh less dense and susceptible to cellular permeability. Thus, the best fibrinogen concentration should be evaluated to find the ideal heterologous fibrin scaffold.

Biological and Medical Aspects Related to South American Rattlesnake Crotalus durissus (Linnaeus, 1758): A View from Colombia

In Colombia, South America, there is a subspecies of the South American rattlesnake Crotalus durissus, C. d. cumanensis, a snake of the Viperidae family, whose presence has been reduced due to the destruction of its habitat. It is an enigmatic snake from the group of pit vipers, venomous, with large articulated front fangs, special designs on its body, and a characteristic rattle on its tail. Unlike in Brazil, the occurrence of human envenomation by C. durisus in Colombia is very rare and contributes to less than 1% of envenomation caused by snakes. Its venom is a complex cocktail of proteins with different biological effects, which evolved with the purpose of paralyzing the prey, killing it, and starting its digestive process, as well as having defense functions. When its venom is injected into humans as the result of a bite, the victim presents with both local tissue damage and with systemic involvement, including a diverse degree of neurotoxic, myotoxic, nephrotoxic, and coagulopathic effects, among others. Its biological effects are being studied for use in human health, including the possible development of analgesic, muscle relaxant, anti-inflammatory, immunosuppressive, anti-infection, and antineoplastic drugs. Several groups of researchers in Brazil are very active in their contributions in this regard. In this work, a review is made of the most relevant biological and medical aspects related to the South American rattlesnake and of what may be of importance for a better understanding of the snake C. d. cumanensis, present in Colombia and Venezuela.

A new multiphase calcium phosphate graft material improves bone healing-An in vitro and in vivo analysis

This study aims to evaluate the potential of a novel biomaterial synthesized from amorphous calcium phosphate (ACP), octacalcium phosphate (OCP), and hydroxyapatite (HA) to repair critical-sized defects (CSD) in rabbit calvaria. In vitro analyses of cell viability, cell proliferation, formation of mineral nodules, and cell differentiation using qPCR were performed for comparing experimental calcium phosphate (ECP), deproteinized bovine bone (DBB), and beta-tricalcium phosphate (β-TCP). Bilateral CSDs were created in 45 rabbit calvaria. Six groups were evaluated: ECP, ECP + fibrin sealant (ECP + S), coagulum, autogenous bone, DBB, and β-TCP. Euthanasia was performed at 2, 4, and 8 weeks, followed by micro-computed tomography and histological and immunohistochemical analyses. Results from in vitro analyses revealed similar biocompatibility for all tested materials and a tendency for higher gene expression of some bone markers in the ECP group than in β-TCP and DBB groups at 7 days. In contrast to that in DBB and β-TCP groups, ECP displayed growing bone volume over total volume percentage (BV/TV%) with time in vivo. Histological analysis revealed a greater number of giant cells and reduced size of grafted particles in ECP during all periods of analysis. RUNX-2 expression was statistically lower in ECP than DBB at 2 and 4 weeks. Despite no statistical significance, ECP presented the highest absolute values for ALP-expression at 2, 4, and 8 weeks compared with other groups. Together, our findings indicate that a combination of the ACP, OCP, and HA phases into ECP is beneficial and promising for bone regeneration.

Effects of a Biocomplex Formed by Two Scaffold Biomaterials, Hydroxyapatite/Tricalcium Phosphate Ceramic and Fibrin Biopolymer, with Photobiomodulation, on Bone Repair

There are several treatment methods available for bone repair, although the effectiveness becomes limited in cases of large defects. The objective of this pre-clinical protocol was to evaluate the grafting of hydroxyapatite/tricalcium phosphate (BCP) ceramic biomaterial (B; QualyBone BCP^®, QualyLive, Amadora, Portugal) together with the heterologous fibrin biopolymer (FB; CEVAP/UNESP Botucatu, Brazil) and with photobiomodulation (PBM; Laserpulse^®, Ibramed, Amparo, Brazil) in the repair process of bone defects. Fifty-six rats were randomly divided into four groups of seven animals each: the biomaterial group (G1/B), the biomaterial plus FB group (G2/BFB); the biomaterial plus PBM group (G3/B + PBM), and the biomaterial plus FB plus PBM group (G4/BFB + PBM). After anesthesia, a critical defect was performed in the center of the rats’ parietal bones, then filled and treated according to their respective groups. The rats were euthanized at 14 and 42 postoperative days. Histomorphologically, at 42 days, the G4/BFB + PBM group showed a more advanced maturation transition, with more organized and mature bone areas forming concentric lamellae. A birefringence analysis of collagen fibers also showed a more advanced degree of maturation for the G4/BFB + PBM group. In the comparison between the groups, in the two experimental periods (14 and 42 days), in relation to the percentage of formation of new bone tissue, a significant difference was found between all groups (G1/B (5.42 ± 1.12; 21.49 ± 4.74), G2/BFB (5.00 ± 0.94; 21.77 ± 2.83), G3/B + PBM (12.65 ± 1.78; 29.29 ± 2.93), and G4/BFB + PBM (12.65 ± 2.32; 31.38 ± 2.89)). It was concluded that the use of PBM with low-level laser therapy (LLLT) positively interfered in the repair process of bone defects previously filled with the biocomplex formed by the heterologous fibrin biopolymer associated with the synthetic ceramic of hydroxyapatite and tricalcium phosphate.

Treatment of partial injury of the calcaneus tendon with heterologous fibrin biopolymer and/or photobiomodulation in rats

The present study aimed to evaluate the new heterologous fibrin biopolymer associated, or not, with photobiomodulation therapy for application in tendon injuries, considered a serious and common orthopedic problem. Thus, 84 Rattus norvegicus had partial transection of the calcaneus tendon (PTCT) and were randomly divided into: control (CG); heterologous fibrin biopolymer (HFB); photobiomodulation (PBM); heterologous fibrin biopolymer + photobiomodulation (HFB + PBM). The animals received HFB immediately after PTCT, while PBM (660 nm, 40 mW, 0.23 J) started 24 h post injury and followed every 24 h for 7, 14, and 21 days. The results of the edema volume showed that after 24 h of PTCT, there was no statistical difference among the groups. After 7, 14, and 21 days, it was observed that the treatment groups were effective in reducing edema when compared to the control. The HFB had the highest edema volume reduction after 21 days of treatment. The treatment groups did not induce tissue necrosis or infections on the histopathological analysis. Tenocyte proliferation, granulation tissue, and collagen formation were observed in the PTCT area in the HFB and HFB + PBM groups, which culminated a better repair process when compared to the CG in the 3 experimental periods. Interestingly, the PBM group revealed, in histological analysis, major tendon injury after 7 days; however, in the periods of 14 and 21 days, the PBM had a better repair process compared to the CG. In the quantification of collagen, there was no statistical difference between the groups in the 3 experimental periods. The findings suggest that the HFB and PBM treatments, isolated or associated, were effective in reducing the volume of the edema, stimulating the repair process. However, the use of HFB alone was more effective in promoting the tendon repair process. Thus, the present study consolidates previous studies of tendon repair with this new HFB. Future clinical trials will be needed to validate this proposal.

Recent advances of 3D hydrogel culture systems for mesenchymal stem cell-based therapy and cell behavior regulation

Mesenchymal stem cells (MSCs) have been increasingly recognized as resources for disease treatments and regenerative medicine. Meanwhile, the unique chemical and physical properties of hydrogels provide innate advantages to achieve...

Effects of Therapy with Fibrin Glue combined with Mesenchymal Stem Cells (MSCs) on Bone Regeneration: A Systematic Review

Cell therapy strategies using mesenchymal stem cells (MSCs) carried in fibrin glue have shown promising results in regenerative medicine. MSCs are crucial for tissue healing because they have angiogenic, anti-apoptotic and immunomodulatory properties, in addition to the ability to differentiate into several specialized cell lines. Fibrin sealant or fibrin glue is a natural polymer involved in the coagulation process. Fibrin glue provides a temporary structure that favors angiogenesis, extracellular matrix deposition and cell-matrix interactions. Additionally, fibrin glue maintains the local and paracrine functions of MSCs, providing tissue regeneration through less invasive clinical procedures. Thus, the objective of this systematic review was to assess the potential of fibrin glue combined with MSCs in bone or cartilage regeneration. The bibliographic search was performed in the PubMed/MEDLINE, LILACS and Embase databases, using the descriptors (“fibrin sealant” OR “fibrin glue”) AND “stem cells” AND “bone regeneration”, considering articles published until 2021. In this case, 12 preclinical and five clinical studies were selected to compose this review, according to the eligibility criteria. In preclinical studies, fibrin glue loaded with MSCs, alone or associated with bone substitute, significantly favored bone defects regeneration compared to scaffold without cells. Similarly, fibrin glue loaded with MSCs presented considerable potential to regenerate joint cartilage injuries and multiple bone fractures, with significant improvement in clinical parameters and absence of postoperative complications. Therefore, there is clear evidence in the literature that fibrin glue loaded with MSCs, alone or combined with bone substitute, is a promising strategy for treating lesions in bone or cartilaginous tissue.

3D-printed nerve guidance conduits multi-functionalized with canine multipotent mesenchymal stromal cells promote neuroregeneration after sciatic nerve injury in rats

Background

Nerve injuries are debilitating, leading to long-term motor deficits. Remyelination and axonal growth are supported and enhanced by growth factor and cytokines. Combination of nerve guidance conduits (NGCs) with adipose-tissue-derived multipotent mesenchymal stromal cells (AdMSCs) has been performing promising strategy for nerve regeneration.

Methods

3D-printed polycaprolactone (PCL)-NGCs were fabricated. Wistar rats subjected to critical sciatic nerve damage (12-mm gap) were divided into sham, autograft, PCL (empty NGC), and PCL + MSCs (NGC multi-functionalized with 10⁶ canine AdMSCs embedded in heterologous fibrin biopolymer) groups. In vitro, the cells were characterized and directly stimulated with interferon-gamma to evaluate their neuroregeneration potential. In vivo, the sciatic and tibial functional indices were evaluated for 12 weeks. Gait analysis and nerve conduction velocity were analyzed after 8 and 12 weeks. Morphometric analysis was performed after 8 and 12 weeks following lesion development. Real-time PCR was performed to evaluate the neurotrophic factors BDNF, GDNF, and HGF, and the cytokine and IL-10. Immunohistochemical analysis for the p75^NTR neurotrophic receptor, S100, and neurofilament was performed with the sciatic nerve.

Results

The inflammatory environment in vitro have increased the expression of neurotrophins BDNF, GDNF, HGF, and IL-10 in canine AdMSCs. Nerve guidance conduits multi-functionalized with canine AdMSCs embedded in HFB improved functional motor and electrophysiological recovery compared with PCL group after 12 weeks. However, the results were not significantly different than those obtained using autografts. These findings were associated with a shift in the regeneration process towards the formation of myelinated fibers. Increased immunostaining of BDNF, GDNF, and growth factor receptor p75^NTR was associated with the upregulation of BDNF, GDNF, and HGF in the spinal cord of the PCL + MSCs group. A trend demonstrating higher reactivity of Schwann cells and axonal branching in the sciatic nerve was observed, and canine AdMSCs were engrafted at 30 days following repair.

Conclusions

3D-printed NGCs multi-functionalized with canine AdMSCs embedded in heterologous fibrin biopolymer as cell scaffold exerted neuroregenerative effects. Our multimodal approach supports the trophic microenvironment, resulting in a pro-regenerative state after critical sciatic nerve injury in rats.

Three dimensional porous scaffolds derived from collagen, elastin and fibrin proteins orchestrate adipose tissue regeneration

Current gold standard to treat soft tissue injuries caused by trauma and pathological condition are autografts and off the shelf fillers, but they have inherent weaknesses like donor site morbidity, immuno-compatibility and graft failure. To overcome these limitations, tissue-engineered polymers are seeded with stem cells to improve the potential to restore tissue function. However, their interaction with native tissue is poorly understood so far. To study these interactions and improve outcomes, we have fabricated scaffolds from natural polymers (collagen, fibrin and elastin) by custom-designed processes and their material properties such as surface morphology, swelling, wettability and chemical cross-linking ability were characterised. By using 3D scaffolds, we comprehensive assessed survival, proliferation and phenotype of adipose-derived stem cells in vitro. In vivo, scaffolds were seeded with adipose-derived stem cells and implanted in a rodent model, with X-ray microtomography, histology and immunohistochemistry as read-outs. Collagen-based materials showed higher cell adhesion and proliferation in vitro as well as higher adipogenic properties in vivo. In contrast, fibrin demonstrated poor cellular and adipogenesis properties but higher angiogenesis. Elastin formed the most porous scaffold, with cells displaying a non-aggregated morphology in vitro while in vivo elastin was the most degraded scaffold. These findings of how polymers present in the natural polymers mimicking ECM and seeded with stem cells affect adipogenesis in vitro and in vivo can open avenues to design 3D grafts for soft tissue repair.

Heterologous fibrin biopolymer associated to a single suture stitch enables the return of neuromuscular junction to its mature pattern after peripheral nerve injury

Denervation leads to severe atrophy of neuromuscular junction (NMJ) structure including decrease of the expression of fundamental proteins. Up to now, conventional suture has been the gold standard method used to correct this injury. Fibrin sealant is one of the alternatives proposed to optimize this method. This study verified if the association of fibrin sealant - Heterologous Fibrin Biopolymer (HFB) and a single suture stitch promotes return of morphology and NMJ structure to mature pattern after peripheral nerve injury. Forty Wistar rats were distributed into 4 groups: Sham-Control (SC), Denervated-Control (DC), Suture-Lesion (SL) and Suture-Lesion + HFB (SFS). In SC group only the right sciatic nerve identification was done. In DC, SL and SFS groups fixation of nerve stumps on musculature immediately after neurotmesis was performed. After seven days, stump reconnection with 3 stitches in SL and a single stitch associated with HFB in SFS were done. After sixty days right soleus muscles were prepared for nicotinic acetylcholine receptors (nAChRs) and nerve terminal confocal analyses, and for nAChRs (α1, ε e γ), S100, Agrin, LRP-4, MMP-3, Rapsyn western blotting analyses. SC group presented normal morphology. In DC group it was observed flattening of NMJ, fragmentation of nAChRs and tangled nerve terminals. The majority of the parameters of SL and SFS groups presented values in between SC and DC groups. There was an increase of relative planar area in these groups (SL and SFS) highlighting that there was less nAChRs fragmentation and the values of protein expression showed return of nAChRs to mature pattern. Use of HFB associated with a single suture stitch decreased surgical time, minimized suture injuries, did not alter nerve regeneration and presented potential to reestablish the NMJ apparatus. These consolidated results encourage surgeons to develop future clinical trials to install definitively this new approach both for reconstructive surgery and neurosurgery.

Treatment of Chronic Venous Ulcers With Heterologous Fibrin Sealant: A Phase I/II Clinical Trial

Background

Heterologous fibrin sealant (HFS) consists of a fibrinogen-rich cryoprecipitate extracted from Bubalus bubalis buffalo blood and a thrombin-like enzyme purified from Crotalus durissus terrificus snake venom. This study evaluated the safety and immunogenicity of HFS, estimated the best dose, and assessed its preliminary efficacy in the treatment of chronic venous ulcers (CVU).

Methods

A phase I/II non-randomized, single-arm clinical trial was performed on 31 participants, accounting for a total of 69 active CVUs. All ulcers were treated with HFS, essential fatty acid, and Unna boot for 12 weeks. The outcomes assessed were: (1) primary safety, immunogenicity analyses, and confirmation of the lowest safe dose; (2) secondary promising efficacy by analyzing the healing process. Immunogenicity was evaluated using the serum-neutralizing (IgM and IgG) and non-neutralizing (IgA and IgE) antibody techniques against the product. The immuno-detection of IgE class antibodies was assessed using dot-blot assay before and at the end of treatment. Positive samples on dot-blot assays were subsequently analyzed by western blotting to verify the results.

Results

No severe systemic adverse events related to the use of HFS were observed. Local adverse events potentially related to treatment include ulcer pain (52%), peri-ulcer maceration (16%), peri-ulcer pruritus (12%), critical colonization (8%), peri-ulcer eczema (4%), the opening of new ulcers (4%), and increased ulcerated area 4%). Neutralizing and non-neutralizing antibodies did not show significant deviations at any of the evaluated time points. Blot assays showed that all patients presented negative immunological reactions, either before or after treatment, with the thrombin-like enzyme component. In addition, two participants showed a positive immunological reaction to the cryoprecipitate component, while another two were positive before and during treatment. Regarding the secondary outcomes of preliminary efficacy, a total healing and significant reduction of the area was observed in 47.5 and 22%, respectively. A qualitative improvement was observed in the wound beds of unhealed ulcers.

Conclusions

The investigational HFS bioproduct proved to be safe and non-immunogenic with a good preliminary efficacy for the treatment of CVU, according to the protocol and doses proposed. A multicentric phase III clinical trial will be necessary to verify these findings.

Photobiomodulation Therapy on the Guided Bone Regeneration Process in Defects Filled by Biphasic Calcium Phosphate Associated with Fibrin Biopolymer

The aim is to evaluate the effects of photobiomodulation therapy (PBMT) on the guided bone regeneration process (GBR) in defects in the calvaria of rats filled with biphasic calcium phosphate associated with fibrin biopolymer. Thirty male Wistar rats were randomly separated: BMG (n = 10), defects filled with biomaterial and covered by membrane; BFMG (n = 10), biomaterial and fibrin biopolymer covered by membrane; and BFMLG (n = 10), biomaterial and fibrin biopolymer covered by membrane and biostimulated with PBMT. The animals were euthanized at 14 and 42 days postoperatively. Microtomographically, in 42 days, there was more evident bone growth in the BFMLG, limited to the margins of the defect with permanence of the particles. Histomorphologically, an inflammatory infiltrate was observed, which regressed with the formation of mineralized bone tissue. In the quantification of bone tissue, all groups had a progressive increase in new bone tissue with a significant difference in which the BFMLG showed greater bone formation in both periods (10.12 ± 0.67 and 13.85 ± 0.54), followed by BFMG (7.35 ± 0.66 and 9.41 ± 0.84) and BMG (4.51 ± 0.44 and 7.11 ± 0.44). Picrosirius-red staining showed greater birefringence of collagen fibers in yellow-green color in the BFMLG, showing more advanced bone maturation. PBMT showed positive effects capable of improving and accelerating the guided bone regeneration process when associated with biphasic calcium phosphate and fibrin biopolymer.

Adipose-Derived Stem Cells: Current Applications and Future Directions in the Regeneration of Multiple Tissues

Adipose-derived stem cells (ADSCs) can maintain self-renewal and enhanced multidifferentiation potential through the release of a variety of paracrine factors and extracellular vesicles, allowing them to repair damaged organs and tissues. Consequently, considerable attention has increasingly been paid to their application in tissue engineering and organ regeneration. Here, we provide a comprehensive overview of the current status of ADSC preparation, including harvesting, isolation, and identification. The advances in preclinical and clinical evidence-based ADSC therapy for bone, cartilage, myocardium, liver, and nervous system regeneration as well as skin wound healing are also summarized. Notably, the perspectives, potential challenges, and future directions for ADSC-related researches are discussed. We hope that this review can provide comprehensive and standardized guidelines for the safe and effective application of ADSCs to achieve predictable and desired therapeutic effects.

Three-dimensional environment and vascularization induce osteogenic maturation of human adipose-derived stem cells comparable to that of bone-derived progenitors

While human adipose‐derived stem cells (hADSCs) are known to possess osteogenic differentiation potential, the bone tissues formed are generally considered rudimentary and immature compared with those made by bone‐derived precursor cells such as human bone marrow‐derived mesenchymal stem cells (hBMSCs) and less commonly studied human calvarium osteoprogenitor cells (hOPs). Traditional differentiation protocols have tended to focus on osteoinduction of hADSCs through the addition of osteogenic differentiation media or use of stimulatory bioactive scaffolds which have not resulted in mature bone formation. Here, we tested the hypothesis that by reproducing the physical as well as biochemical bone microenvironment through the use of three‐dimensional (3D) culture and vascularization we could enhance osteogenic maturation in hADSCs. In addition to biomolecular characterization, we performed structural analysis through extracellular collagen alignment and mineral density in our bone tissue engineered samples to evaluate osteogenic maturation. We further compared bone formed by hADSCs, hBMSCs, and hOPs against mature human pediatric calvarial bone, yet not extensively investigated. Although bone generated by all three cell types was still less mature than native pediatric bone, a fibrin‐based 3D microenvironment together with vascularization boosted osteogenic maturation of hADSC making it similar to that of bone‐derived osteoprogenitors. This demonstrates the important role of vascularization and 3D culture in driving osteogenic maturation of cells easily available but constitutively less committed to this lineage and suggests a crucial avenue for recreating the bone microenvironment for tissue engineering of mature craniofacial bone tissues from pediatric hADSCs, as well as hBMSCs and hOPs.

Highly effective fibrin biopolymer scaffold for stem cells upgrading bone regeneration

Fibrin scaffold fits as a provisional platform promoting cell migration and proliferation, angiogenesis, connective tissue formation and growth factors stimulation. We evaluated a unique heterologous fibrin biopolymer as scaffold to mesenchymal stem cells (MSCs) to treat a critical-size bone defect. Femurs of 27 rats were treated with fibrin biopolymer (FBP); FBP + MSCs; and FBP + MSC differentiated in bone lineage (MSC-D). Bone repair was evaluated 03, 21 and 42 days later by radiographic, histological and scanning electron microscopy (SEM) imaging. The FBP + MSC-D association was the most effective treatment, since newly formed Bone was more abundant and early matured in just 21 days. We concluded that FBP is an excellent scaffold for MSCs and also use of differentiated cells should be encouraged in regenerative therapy researches. The FBP ability to maintain viable MSCs at Bone defect site has modified inflammatory environment and accelerating their regeneration.

Photobiomodulation Therapy Associated with Heterologous Fibrin Biopolymer and Bovine Bone Matrix Helps to Reconstruct Long Bones

Bone defects cause aesthetic and functional changes that affect the social, economic and especially the emotional life of human beings. This complication stimulates the scientific community to investigate strategies aimed at improving bone reconstruction processes using complementary therapies. Photobiomodulation therapy (PBMT) and the use of new biomaterials, including heterologous fibrin biopolymer (HFB), are included in this challenge. The objective of the present study was to evaluate the influence of photobiomodulation therapy on bone tibial reconstruction of rats with biomaterial consisting of lyophilized bovine bone matrix (BM) associated or not with heterologous fibrin biopolymer. Thirty male rats were randomly separated into three groups of 10 animals. In all animals, after the anesthetic procedure, a noncritical tibial defect of 2 mm was performed. The groups received the following treatments: Group 1: BM + PBMT, Group 2: BM + HFB and Group 3: BM + HFB + PBMT. The animals from Groups 1 and 3 were submitted to PBMT in the immediate postoperative period and every 48 h until the day of euthanasia that occurred at 14 and 42 days. Analyses by computed microtomography (µCT) and histomorphometry showed statistical difference in the percentage of bone formation between Groups 3 (BM + HB + PBMT) and 2 (BM + HFB) (26.4% ± 1.03% and 20.0% ± 1.87%, respectively) at 14 days and at 42 days (38.2% ± 1.59% and 31.6% ± 1.33%, respectively), and at 42 days there was presence of bone with mature characteristics and organized connective tissue. The µCT demonstrated BM particles filling the defect and the deposition of new bone in the superficial region, especially in the ruptured cortical. It was concluded that the association of PBMT with HFB and BM has the potential to assist in the process of reconstructing bone defects in the tibia of rats.

Unique heterologous fibrin biopolymer with hemostatic, adhesive, sealant, scaffold and drug delivery properties: a systematic review

Fibrin biopolymers, previously referred as "fibrin glue" or "fibrin sealants", are natural biomaterials with diverse applications on health. They have hemostatic, adhesive, sealant, scaffold and drug delivery properties and have become widely used in medical and dental procedures. Historically, these biomaterials are produced from human fibrinogen and human or animal thrombin, and the possibility of transmission of infectious diseases by human blood is not ruled out. In the 1990s, to overcome this problem, a new heterologous biomaterial composed of a thrombin-like enzyme purified from Crotalus durissus terrificus venom and a cryoprecipitate rich in fibrinogen extracted from buffaloes Bubalus bubalis blood has been proposed. Therefore, a systematic review of studies on exclusively heterologous fibrin sealants published between 1989 and 2018 was carried out using the following databases: PubMed, SciELO and Google Scholar. The keyword used was "heterologous fibrin sealant". The search resulted in 35 scientific papers in PubMed, four in SciELO and 674 in Google Scholar. After applying the inclusion/exclusion criteria and complete reading of the articles, 30 studies were selected, which formed the basis of this systematic review. It has been observed that the only completely heterologous sealant is the one produced by CEVAP/UNESP. This heterologous biopolymer is proven effective by several studies published in refereed scientific journals. In addition, clinical trials phase I/II for the treatment of chronic venous ulcers authorized by the Brazilian Health Regulatory Agency (ANVISA) were completed. Preliminary results have indicated a safe and promising effective product. Phase III clinical trials will be proposed and required to validate these preliminary findings.

Fibrin biopolymer as scaffold candidate to treat bone defects in rats

BACKGROUND

Bone tissue repair remains a challenge in tissue engineering. Currently, new materials are being applied and often integrated with live cells and biological scaffolds. The fibrin biopolymer (FBP) proposed in this study has hemostatic, sealant, adhesive, scaffolding and drug-delivery properties. The regenerative potential of an association of FBP, biphasic calcium phosphate (BCP) and mesenchymal stem cells (MSCs) was evaluated in defects of rat femurs.

METHODS

Adult male Wistar rats were submitted to a 5-mm defect in the femur. This was filled with the following materials and/or associations: BPC; FBP and BCP; FBP and MSCs; and BCP, FBP and MSCs. Bone defect without filling was defined as the control group. Thirty and sixty days after the procedure, animals were euthanatized and subjected to computed tomography, scanning electron microscopy and qualitative and quantitative histological analysis.

RESULTS

It was shown that FBP is a suitable scaffold for bone defects due to the formation of a stable clot that facilitates the handling and optimizes the surgical procedures, allowing also cell adhesion and proliferation. The association between the materials was biocompatible. Progressive deposition of bone matrix was higher in the group treated with FBP and MSCs. Differentiation of mesenchymal stem cells into osteogenic lineage was not necessary to stimulate bone formation.

CONCLUSIONS

FBP proved to be an excellent scaffold candidate for bone repair therapies due to application ease and biocompatibility with synthetic calcium-based materials. The satisfactory results obtained by the association of FBP with MSCs may provide a more effective and less costly new approach for bone tissue engineering.

Bioprinting functional tissues

Despite the numerous lives that have been saved since the first successful procedure in 1954, organ transplant has several shortcomings which prevent it from becoming a more comprehensive solution for medical care than it is today. There is a considerable shortage of organ donors, leading to patient death in many cases. In addition, patients require lifelong immunosuppression to prevent graft rejection postoperatively. With such issues in mind, recent research has focused on possible solutions for the lack of access to donor organs and rejections, with the possibility of using the patient's own cells and tissues for treatment showing enormous potential. Three-dimensional (3D) bioprinting is a rapidly emerging technology, which holds great promise for fabrication of functional tissues and organs. Bioprinting offers the means of utilizing a patient's cells to design and fabricate constructs for replacement of diseased tissues and organs. It enables the precise positioning of cells and biologics in an automated and high throughput manner. Several studies have shown the promise of 3D bioprinting. However, many problems must be overcome before the generation of functional tissues with biologically-relevant scale is possible. Specific focus on the functionality of bioprinted tissues is required prior to clinical translation. In this perspective, this paper discusses the challenges of functionalization of bioprinted tissue under eight dimensions: biomimicry, cell density, vascularization, innervation, heterogeneity, engraftment, mechanics, and tissue-specific function, and strives to inform the reader with directions in bioprinting complex and volumetric tissues. STATEMENT OF SIGNIFICANCE: With thousands of patients dying each year waiting for an organ transplant, bioprinted tissues and organs show the potential to eliminate this ever-increasing organ shortage crisis. However, this potential can only be realized by better understanding the functionality of the organ and developing the ability to translate this to the bioprinting methodologies. Considering the rate at which the field is currently expanding, it is reasonable to expect bioprinting to become an integral component of regenerative medicine. For this purpose, this paper discusses several factors that are critical for printing functional tissues including cell density, vascularization, innervation, heterogeneity, engraftment, mechanics, and tissue-specific function, and inform the reader with future directions in bioprinting complex and volumetric tissues.

Functional and biological insights of rCollinein-1, a recombinant serine protease from Crotalus durissus collilineatus

BACKGROUND

The prevalent class of snake venom serine proteases (SVSP) in Viperidae venoms is the thrombin-like enzymes, which, similarly to human thrombin, convert fibrinogen into insoluble fibrin monomers. However, thrombin-like serine proteases differ from thrombin by being unable to activate factor XIII, thus leading to the formation of loose clots and fibrinogen consumption. We report the functional and biological characterization of a recombinant thrombin-like serine protease from Crotalus durissus collilineatus, named rCollinein-1.

METHODS

Heterologous expression of rCollinein-1 was performed in Pichia pastoris system according to a previously standardized protocol, with some modifications. rCollinein-1 was purified from the culture medium by a combination of three chromatographic steps. The recombinant toxin was tested in vitro for its thrombolytic activity and in mice for its edematogenicity, blood incoagulability and effect on plasma proteins.

RESULTS

When tested for the ability to induce mouse paw edema, rCollinein-1 demonstrated low edematogenic effect, indicating little involvement of this enzyme in the inflammatory processes resulting from ophidian accidents. The rCollinein-1 did not degrade blood clots in vitro, which suggests that this toxin lacks fibrinolytic activity and is not able to directly or indirectly activate the fibrinolytic system. The minimal dose of rCollinein-1 that turns the blood incoagulable in experimental mice is 7.5 mg/kg. The toxin also led to a significant increase in activated partial thromboplastin time at the dose of 1 mg/kg in the animals. Other parameters such as plasma fibrinogen concentration and prothrombin time were not significantly affected by treatment with rCollinein-1 at this dose. The toxin was also able to alter plasma proteins in mouse after 3 h of injection at a dose of 1 mg/kg, leading to a decrease in the intensity of beta zone and an increase in gamma zone in agarose gel electrophoresis.

CONCLUSION

These results suggest that the recombinant enzyme has no potential as a thrombolytic agent but can be applied in the prevention of thrombus formation in some pathological processes and as molecular tools in studies related to hemostasis.

Heterologous fibrin sealant potentiates axonal regeneration after peripheral nerve injury with reduction in the number of suture points

The use of suture associated with heterologous fibrin sealant has been highlighted for reconstruction after peripheral nerve injury, having the advantage of being safe for clinical use. In this study we compared the use of this sealant associated with reduced number of stitches with conventional suture after ischiatic nerve injury. 36 Wistar rats were divided into 4 groups: Control (C), Denervated (D), ischiatic nerve neurotmesis (6 mm gap); Suture (S), epineural anastomosis after 7 days from neurotmesis, Suture + Fibrin Sealant (SFS), anastomosis with only one suture point associated with Fibrin Sealant. Catwalk, electromyography, ischiatic and tibial nerve, soleus muscle morphological and morphometric analyses were performed. The amplitude and latency values of the Suture and Suture + Fibrin Sealant groups were similar and indicative of nerve regeneration.The ischiatic nerve morphometric analysis in the Suture + Fibrin Sealant showed superior values related to axons and nerve fibers area and diameter when compared to Suture group. In the Suture and Suture + Fibrin Sealant groups, there was an increase in muscle weight and in fast fibers frequency, it was a decrease in the percentage of collagen compared to group Denervated and in the neuromuscular junctions, the synaptic boutons were reestablished.The results suggest a protective effect at the lesion site caused by the fibrin sealant use. The stitches reduction minimizes the trauma caused by the needle and it accelerates the surgical practice. So the heterologous fibrin sealant use in nerve reconstruction should be considered.

Low-level laser and adipose-derived stem cells altered remodelling genes expression and improved collagen reorganization during tendon repair

Objectives

The cellular therapy using adipose‐derived mesenchymal stem cells (ASCs) aims to improve tendon healing, considering that repaired tendons often result in a less resistant tissue. Our objective was to evaluate the effects of the ASCs combination with a low‐level laser (LLL), an effective photobiostimulation for the healing processes.

Materials and methods

Rats calcaneal tendons were divided into five groups: normal (NT), transected (T), transected and ASCs (SC) or LLL (L), or with ASCs and LLL (SCL).

Results

All treated groups presented higher expression of Dcn and greater organization of collagen fibres. In comparison with T, LLL also up‐regulated Gdf5 gene expression, ASCs up‐regulated the expression of Tnmd, and the association of LLL and ASCs down‐regulated the expression of Scx. No differences were observed for the expression of Il1b, Timp2, Tgfb1, Lox, Mmp2, Mmp8 and Mmp9, neither in the quantification of hydroxyproline, TNF‐α, PCNA and in the protein level of Tnmd. A higher amount of IL‐10 was detected in SC, L and SCL compared to T, and higher amount of collagen I and III was observed in SC compared to SCL.

Conclusions

Transplanted ASCs migrated to the transected region, and all treatments altered the remodelling genes expression. The LLL was the most effective in the collagen reorganization, followed by its combination with ASCs. Further investigations are needed to elucidate the molecular mechanisms involved in the LLL and ASCs combination during initial phases of tendon repair.

Transected Tendon Treated with a New Fibrin Sealant Alone or Associated with Adipose-Derived Stem Cells

Tissue engineering and cell-based therapy combine techniques that create biocompatible materials for cell survival, which can improve tendon repair. This study seeks to use a new fibrin sealant (FS) derived from the venom of Crotalus durissus terrificus, a biodegradable three-dimensional scaffolding produced from animal components only, associated with adipose-derived stem cells (ASC) for application in tendons injuries, considered a common and serious orthopedic problem. Lewis rats had tendons distributed in five groups: normal (N), transected (T), transected and FS (FS) or ASC (ASC) or with FS and ASC (FS + ASC). The in vivo imaging showed higher quantification of transplanted PKH26-labeled ASC in tendons of FS + ASC compared to ASC on the 14th day after transection. A small number of Iba1 labeled macrophages carrying PKH26 signal, probably due to phagocytosis of dead ASC, were observed in tendons of transected groups. ASC up-regulated the Tenomodulin gene expression in the transection region when compared to N, T and FS groups and the expression of TIMP-2 and Scleraxis genes in relation to the N group. FS group presented a greater organization of collagen fibers, followed by FS + ASC and ASC in comparison to N. Tendons from ASC group presented higher hydroxyproline concentration in relation to N and the transected tendons of T, FS and FS + ASC had a higher amount of collagen I and tenomodulin in comparison to N group. Although no marked differences were observed in the other biomechanical parameters, T group had higher value of maximum load compared to the groups ASC and FS + ASC. In conclusion, the FS kept constant the number of transplanted ASC in the transected region until the 14th day after injury. Our data suggest this FS to be a good scaffold for treatment during tendon repair because it was the most effective one regarding tendon organization recovering, followed by the FS treatment associated with ASC and finally by the transplanted ASC on the 21st day. Further investigations in long-term time points of the tendon repair are needed to analyze if the higher tissue organization found with the FS scaffold will improve the biomechanics of the tendons.

A totally recombinant fibrin matrix for mesenchymal stem cell culture and delivery

Mesenchymal stem cells (MSCs) have been widely studied for tissue engineering and treating diseases in laboratories, clinical trials, and clinics. Fibrin matrices are often used to culture MSCs or increase the retention of MSCs at the injection site. However, fibrins made with the human plasma derived fibrinogen have high cost and risk of human pathogen transmission. In this article, we studied if fibrin matrices made with recombinant human fibrinogen, recombinant human thrombin, and recombinant human factor XIII could be used to culture and deliver MSCs. We systematically investigated the relationships between the fibrin matrix formulation, its nanostructure, and the behaviors of the cells in the matrix including the cell morphology, viability, and growth. We found that the fibrinogen concentration significantly affected the matrix structure and cell behaviors. We then used an optimized fibrin matrix to deliver human MSCs into mice subcutaneously. We found that the matrix could significantly enhance the retention of MSCs at the injection site. To our best knowledge, this is the first study on using fibrin matrices made with entirely recombinant proteins for culturing and delivering MSCs. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3135-3142, 2018.

BjSP, a novel serine protease from Bothrops jararaca snake venom that degrades fibrinogen without forming fibrin clots

Snake venom serine proteases (SVSPs) are commonly described as capable of affecting hemostasis by interacting with several coagulation system components. In this study, we describe the isolation and characterization of BjSP from Bothrops jararaca snake venom, a serine protease with distinctive properties. This enzyme was isolated by three consecutive chromatographic steps and showed acidic character (pI 4.4), molecular mass of 28 kDa and N-carbohydrate content around 10%. Its partial amino acid sequence presented 100% identity to a serine protease cDNA clone previously identified from B. jararaca venom gland, but not yet isolated or characterized. BjSP was significantly inhibited by specific serine protease inhibitors and showed high stability at different pH values and temperatures. The enzyme displayed no effects on washed platelets, but was able to degrade fibrin clots in vitro and also the Aα and Bβ chains of fibrinogen differently from thrombin, forming additional fibrinopeptides derived from the Bβ chain, which should be related to its inability to coagulate fibrinogen solutions or platelet-poor plasma. In the mapping of catalytic subsites, the protease showed high hydrolytic specificity for tyrosine, especially in subsite S1. Additionally, its amidolytic activity on different chromogenic substrates suggests possible effects on other factors of the coagulation cascade. In conclusion, BjSP is a serine protease that acts nonspecifically on fibrinogen, generating different Bβ fibrinopeptides and thus not forming fibrin clots. Its distinguished properties in comparison to most SVSPs stimulate further studies in an attempt to validate its potential as a defibrinogenating agent.

Combination of heterologous fibrin sealant and bioengineered human embryonic stem cells to improve regeneration following autogenous sciatic nerve grafting repair

Background

Peripheral nerve injury is a worldwide clinical problem, and the preferred surgical method for treating it is the end-to-end neurorrhaphy. When it is not possible due to a large nerve gap, autologous nerve grafting is used. However, these surgical techniques result in nerve regeneration at highly variable degrees. It is thus very important to seek complementary techniques to improve motor and sensory recovery. One promising approach could be cell therapy. Transplantation therapy with human embryonic stem cells (hESCs) is appealing because these cells are pluripotent and can differentiate into specialized cell types and have self-renewal ability. Therefore, the main objective of this study was to find conditions under which functional recovery is improved after sciatic nerve neurorrhaphy. We assumed that hESC, either alone or in combination with heterologous fibrin sealant scaffold, could be used to support regeneration in a mouse model of sciatic nerve injury and repair via autografting with end-to-end neurorrhaphy.

Methods

Five millimeters of the sciatic nerve of C57BL/6 J mice were transected off and rotated 180 degrees to simulate an injury, and then stumps were sutured. Next, we applied heterologous fibrin sealant and/or human embryonic stem cells genetically altered to overexpress fibroblast growth factor 2 (FGF2) at the site of the injury. The study was designed to include six experimental groups comprising neurorrhaphy (N), neurorrhaphy + heterologous fibrin sealant (N + F), neurorrhaphy + heterologous fibrin sealant + doxycycline (N + F + D), neurorrhaphy + heterologous fibrin sealant + wild-type hESC (N + F + W), neurorrhaphy + heterologous fibrin sealant + hESC off (N + F + T), and neurorrhaphy + heterologous fibrin sealant + hESC on via doxycycline (N + F + D + T). We evaluated the recovery rate using Catwalk and von Frey functional recovery tests, as well as immunohistochemistry analysis.

Results

The experiments indicated that sensory function improved when transgenic hESCs were used. The regeneration of sensory fibers indeed led to increased reflexes, upon stimulation of the paw ipsilateral to the lesion, as seen by von-Frey evaluation, which was supported by immunohistochemistry.

Conclusions

Overall, the present data demonstrated that transgenic embryonic stem cells, engineered to overexpress FGF-2 in an inducible fashion, could be employed to support regeneration aiming at the recovery of both motor and sensory functions.

Low-Intensity Ultrasound Upregulates the Expression of Cyclin-D1 and Promotes Cellular Proliferation in Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSCs) hold great potential for cellular based therapeutics and tissue engineering applications and their expansion is an interesting prospect due to their low availability from in vivo sources. Therefore, this study investigated the effect of continuous-wave low-intensity ultrasound (LIUS) at 5.0-MHz and 14.0-kPa (<20 mW cm^-2 ) on the proliferative capacity, colony-formation efficiency, genetic stability, and differentiation potential of hMSCs. Additionally, potential signaling pathways involved in LIUS-mediated proliferation of hMSCs are studied. Compared to non-stimulated controls, LIUS-treated hMSCs shows a 1.9-fold greater colony-forming efficiency and 2.5-fold higher rate of cell proliferation, respectively. Differential staining and qRT-PCR analysis for selective chondrogenic, osteogenic, and adipogenic markers further confirmed that the LIUS treatment did not impact the multipotency of hMSCs. LIUS-treated hMSCs expressed normal male karyotype. The synthesis of cyclin-D1, a master regulator of cellular proliferation, is upregulated under LIUS and its enhanced mRNA expression under LIUS is noted to be mediated by the activation of both MAPK/ERK and PI3K/AKT pathways. In conclusion, LIUS promotes proliferation and self-renewal capacity of hMSCs.

17β-estradiol improves the efficacy of exploited autologous bone marrow-derived mesenchymal stem cells in non-union radial defect healing: A rabbit model

Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more qualified approach that yields in a shorter time appears to be promising for the future cell-based clinical treatments of the non-union bone fractures. Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on the radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more efficient approach that yields in a shorter time appears to be promising for future cell-based clinical treatments of the non-union bone fractures.

A unique heterologous fibrin sealant (HFS) as a candidate biological scaffold for mesenchymal stem cells in osteoporotic rats

Background

The injection of mesenchymal stem cells (MSCs) directly into the bone of osteoporotic (OP) patients for rapid recovery has been studied worldwide. Scaffolds associated with MSCs are used to maintain and avoid cell loss after application. A unique heterologous fibrin sealant (HFS) derived from snake venom was evaluated for the cytotoxicity of its main components and as a three-dimensional biological scaffold for MSCs to repair a critical femur defect in osteoporotic rats.

Methods

The cytotoxicity of HFS was assessed using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay and transmission electron microscopy. The cells were cultured, characterized by flow cytometry and differentiated into the osteogenic lineage. Two-month-old rats underwent ovariectomy to induce OP. After 3 months, a 5 mm critical bone defect was made in the distal end of the rat femurs and filled with HFS; HFS + MSCs; and HFS + MSCs D (differentiated into the osteogenic lineage) to evaluate the effects. An injury control group (injury and no treatment) and blank control group (no injury and no treatment) were also included. The animals were observed at days 14 and 28 by microtomographic (micro-CT) analyses, histologic and biochemical analysis, as well as scanning electron microscopy.

Results

The results revealed that one of the compounds of HFS, the thrombin-like enzyme extracted from snake venom, had no cytotoxic effects on the MSCs. OP was successfully induced, as demonstrated by the significant differences in the levels of 17β-estradiol, Micro-CT analyses and alkaline phosphatase between the ovariectomized (OVX) and non-ovariectomized (NOVX) groups. The histological data revealed that at 14 days after surgery in both the OVX and NOVX animals, the HFS + CTMs and HFS + CTMsD showed a higher formation of bone cells at the site in relation to the control group (without treatment). Collagen formation was evidenced through bone neoformation in all treated and control groups. No morphological differences in the femurs of the NOVX and OVX animals were observed after the surgical procedure. Scanning electron microscopy (SEM) confirmed the histological analysis.

Conclusions

The new HFS composed of two non-toxic components for MSCs showed capacity to promote the recovery of the bone lesions in OVX and NOVX animals at 14 days after surgery. In addition, the HFS enabled the differentiation of MSCs into MSCs D in the group treated with HFS + MSCs. Using the MSCs and/or MSCs D together with this biopharmaceutical could potentially enable significant advances in the treatment of osteoporotic fractures. Future clinical trials will be necessary to confirm these results.

Stimulation of morphofunctional repair of the facial nerve with photobiomodulation, using the end-to-side technique or a new heterologous fibrin sealant

This research evaluated the influence of Photobiomodulation Therapy (PBMT) on lesions of the facial nerve repaired with the end-to-side technique or coaptation with a new heterologous fibrin sealant. Thirty-two Wistar rats were separated into 5 groups: Control group (CG), where the buccal branch of the facial nerve was collected; Experimental Suture Group (ESG) and Experimental Fibrin Group (EFG), in which the buccal branch was end-to-side sutured to the zygomatic branch on the right side of the face or coaptated with fibrin sealant on the left side; Experimental Suture Laser Group (ESLG) and Experimental Fibrin Laser Group (EFLG), in which the same procedures were performed as the ESG and EFG, associated with PBMT (wavelength of 830nm, energy density 6.2J/cm², power output 30mW, beam area of 0.116cm², power density 0.26W/cm², total energy per session 2.16J, cumulative dose of 34.56J). The laser was applied for 24s/site at 3 points on the skin's surface, for a total application time of 72s, performed immediately after surgery and 3 times a week for 5weeks. A statistically significant difference was observed in the fiber nerve area between the EFG and EFLG (57.49±3.13 and 62.52±3.56μm², respectively). For the area of the axon, fiber diameter, axon diameter, myelin sheath area and myelin sheath thickness no statistically significant differences were found (p<0.05). The functional recovery of whisker movement occurred faster in the ESLG and EFLG, which were associated with PBMT, with results closer to the CG. Therefore, PBMT accelerated morphological and functional nerve repair in both techniques.

Plasma proteome of buffaloes

The proteomic approach has aroused the interest of veterinary medicine researchers, especially regarding the production of biopharmaceuticals and diagnosis of diseases in farm animals. Water buffaloes have gained prominence in the world economy due to the quality of their milk, meat, and leather, in addition to being an important donor of blood components. This work aimed to identify and characterize the proteins present in the blood plasma of Murrah buffaloes (Bubalus bubalis) through 2D electrophoresis, in gel protein digestion followed by mass spectrometry technique and for albumin depletion, in solution protein digestion followed by shotgun analysis. Our results showed the identification of 112 protein spots and 35 individual proteins, respectively. The abundant proteins were represented by albumin, fibrinogen-α, fibrinogen-β, fibrinogen-γ, immunoglobulins in general, α-1-antiproteinase, α-1B-glycoprotein, α-2-HS-glycoprotein, α-macroglobulin, apolipoprotein A1, antithrombin-III, endopin 2B, fetuin-B, retinol-binding protein, serotransferrin, transthyretin and vitamin D-binding protein. Most of these proteins are related to the signaling pathways of the complement system and coagulation cascade. The results allowed a better understanding of the protein composition of these blood components, thus promoting studies on animal health in the search for molecular markers of zoonotic diseases in buffaloes.

Efficacy of Laser Photobiomodulation on Morphological and Functional Repair of the Facial Nerve

OBJECTIVE

Evaluate the efficacy of low-level laser therapy (LLLT) on qualitative, quantitative, and functional aspects in the facial nerve regeneration process.

MATERIALS AND METHODS

Forty-two male Wistar rats were used, randomly divided into a control group (CG; n = 10), in which the facial nerve without lesion was collected, and four experimental groups: (1) suture experimental group (SEG) and (2) fibrin experimental group (FEG), consisting of 16 animals in which the buccal branch of the facial nerve was sectioned on both sides of the face; an end-to-end epineural suture was performed on the right side, and a fibrin sealant was used on the left side for coaptation of the stumps; and (3) laser suture experimental group (LSEG) and (4) laser fibrin experimental group (LFEG), consisting of 16 animals that underwent the same surgical procedures as SEG and FEG with the addition of laser application at three different points along the surgical site (pulsed laser of 830 nm wavelength, optical output power of 30 mW, power density of 0.2586 W/cm², energy density of 6.2 J/cm², beam area of 0.116 cm², exposure time of 24 sec per point, total energy per session of 2.16 J, and cumulative dose of 34.56 J). The animals were submitted to functional analysis (subjective observation of whisker movement) and the data obtained were compared using Fisher's exact test. Euthanasia was performed at 5 and 10 weeks postoperative. The total number and density of regenerated axons were analyzed using the unpaired t-test (p < 0.05).

RESULTS

Laser therapy resulted in a significant increase in the number and density of regenerated axons. The LSEG and LFEG presented better scores in functional analysis in comparison with the SEG and FEG.

CONCLUSIONS

LLLT enhanced axonal regeneration and accelerated functional recovery of the whiskers, and both repair techniques allowed the growth of axons.

Heterologous fibrin sealant derived from snake venom: from bench to bedside - an overview

Hemostatic and adhesive agents date back to World War II, when homologous fibrin sealant came onto scene. Considering that infectious diseases can be transmitted via human blood, a new heterologous fibrin sealant was standardized in the 1990s. Its components were a serine protease (a thrombin-like enzyme) extracted from the venom of Crotalus durissus terrificus snakes and a fibrinogen-rich cryoprecipitate extracted from the blood of Bubalus bubalis buffaloes. This new bioproduct has been used as a coagulant, sealant, adhesive and recently as a candidate scaffold for mesenchymal stem cells and bone and cartilage repair. This review discusses the composition of a new heterologous fibrin sealant, and cites published articles related to its preclinical applications aiming at repairing nervous system traumas and regenerating bone marrow. Finally, we present an innovative safety trial I/II that found the product to be a safe and clinically promising candidate for treating chronic venous ulcers. A multicenter clinical trial, phase II/III, with a larger number of participants will be performed to prove the efficacy of an innovative biopharmaceutical product derived from animal venom.

Adipose-derived stem cells in cartilage regeneration: current perspectives

Repair of cartilage injuries represents a musculoskeletal medicine criticism because of the poor ability to self-renewal of adult cartilage. Therefore, research focuses on developing new regenerative strategies combining chondrocytes or stem cells, scaffolds and growth factors. Because of the low proliferation capability of explanted chondrocytes, new chondrogenesis models, employing human adipose-derived stem cells (ASCs), have been investigated. ASCs are readily accessible with no morbidity and display the capability to differentiate into several cell lineages, including the spontaneous chondrogenic differentiation when entrapped in collagen gel scaffolds. Recent studies also defined some biomolecular mechanisms involved in ASC chondrogenesis in vitro, and their regenerative properties in bioengineered scaffolds and in the presence of growth factors. However, further investigations are required to validate these exciting preclinical results for the application of bioenginereed ASCs in the clinical practice.

Effect of Blood Component Coatings of Enosseal Implants on Proliferation and Synthetic Activity of Human Osteoblasts and Cytokine Production of Peripheral Blood Mononuclear Cells

The study monitored in vitro early response of connective tissue cells and immunocompetent cells to enosseal implant materials coated by different blood components (serum, activated plasma, and plasma/platelets) to evaluate human osteoblast proliferation and synthetic activity and inflammatory response presented as a cytokine profile of peripheral blood mononuclear cells (PBMCs) under conditions imitating the situation upon implantation. The cells were cultivated on coated Ti-plasma-sprayed (Ti-PS), Ti-etched (Ti-Etch), Ti-hydroxyapatite (Ti-HA), and ZrO₂ surfaces. The plasma/platelets coating supported osteoblast proliferation only on osteoconductive Ti-HA and Ti-Etch whereas activated plasma enhanced proliferation on all surfaces. Differentiation (BAP) and IL-8 production remained unchanged or decreased irrespective of the coating and surface; only the serum and plasma/platelets-coated ZrO₂ exhibited higher BAP and IL-8 expression. RANKL production increased on serum and activated plasma coatings. PBMCs produced especially cytokines playing role in inflammatory phase of wound healing, that is, IL-6, GRO-α, GRO, ENA-78, IL-8, GM-CSF, EGF, and MCP-1. Cytokine profiles were comparable for all tested surfaces; only ENA-78, IL-8, GM-CSF, and MCP-1 expression depended on materials and coatings. The activated plasma coating led to uniformed surfaces and represented a favorable treatment especially for bioinert Ti-PS and ZrO₂ whereas all coatings had no distinctive effect on bioactive Ti-HA and Ti-Etch.

Direct Spinal Ventral Root Repair following Avulsion: Effectiveness of a New Heterologous Fibrin Sealant on Motoneuron Survival and Regeneration

Axonal injuries at the interface between central and peripheral nervous system, such as ventral root avulsion (VRA), induce important degenerative processes, mostly resulting in neuronal and motor function loss. In the present work, we have compared two different fibrin sealants, one derived from human blood and another derived from animal blood and Crotalus durissus terrificus venom, as a promising treatment for this type of injury. Lewis rats were submitted to VRA (L4–L6) and had the avulsed roots reimplanted to the surface of the spinal cord, with the aid of fibrin sealant. The spinal cords were processed to evaluate neuronal survival, synaptic stability, and glial reactivity, 4 and 12 weeks after lesion. Sciatic nerves were processed to investigate Schwann cell activity by p75^NTR expression (4 weeks after surgery) and to count myelinated axons and morphometric evaluation (12 weeks after surgery). Walking track test was used to evaluate gait recovery, up to 12 weeks. The results indicate that both fibrin sealants are similarly efficient. However, the snake-derived fibrin glue is a potentially safer alternative for being a biological and biodegradable product which does not contain human blood derivatives. Therefore, the venom glue can be a useful tool for the scientific community due to its advantages and variety of applications.

Effects of low-level laser therapy on autogenous bone graft stabilized with a new heterologous fibrin sealant

Autogenous bone grafts are used to repair bone defects, and the stabilization is needed for bone regeneration. Laser photobiomodulation is a modality of treatment in clinical practice for tissue regeneration, and it has therapeutic effects as an anti-inflammatory, analgesic and modulating cellular activity. The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on an autogenous bone graft integration process stabilized with a new heterologous fibrin sealant. Forty rats were divided into two groups: Autogenous Fibrin Graft (AFG, n=20), in which a 5mm dome osteotomy was conducted in the right parietal bone and the graft was adhered to the left side using fibrin sealant; and Autogenous Fibrin Graft Laser (AFGL, n=20), which was subjected to the same procedures as AFG with the addition of LLLT. The treatment was performed immediately following surgery and then three times a week until euthanasia, using an 830nm laser (30mW, 6J/cm(2), 0.116cm(2), 258.6mW/cm(2), 2.9J). Five animals from each group were euthanized at 10, 20, 30 and 40days postoperative, and the samples were submitted to histomorphological and histomorphometric analysis. Partial bone regeneration occurred, with new bone tissue integrating the graft to the recipient bed and small areas of connective tissue. Comparative analysis of the groups at the same intervals revealed minor interfaces in group AFGL, with statistically significant differences (p<0.05) at all of the analyzed intervals (10days p=0.0087, 20days p=0.0012, 30days p<0.0001, 40days p=0.0142). In conclusion, low-level laser therapy stimulated bone regeneration and accelerated the process of integration of autogenous bone grafts.

Long-Standing Motor and Sensory Recovery following Acute Fibrin Sealant Based Neonatal Sciatic Nerve Repair

Brachial plexus lesion results in loss of motor and sensory function, being more harmful in the neonate. Therefore, this study evaluated neuroprotection and regeneration after neonatal peripheral nerve coaptation with fibrin sealant. Thus, P2 neonatal Lewis rats were divided into three groups: AX: sciatic nerve axotomy (SNA) without treatment; AX+FS: SNA followed by end-to-end coaptation with fibrin sealant derived from snake venom; AX+CFS: SNA followed by end-to-end coaptation with commercial fibrin sealant. Results were analyzed 4, 8, and 12 weeks after lesion. Astrogliosis, microglial reaction, and synapse preservation were evaluated by immunohistochemistry. Neuronal survival, axonal regeneration, and ultrastructural changes at ventral spinal cord were also investigated. Sensory-motor recovery was behaviorally studied. Coaptation preserved synaptic covering on lesioned motoneurons and led to neuronal survival. Reactive gliosis and microglial reaction decreased in the same groups (AX+FS, AX+CFS) at 4 weeks. Regarding axonal regeneration, coaptation allowed recovery of greater number of myelinated fibers, with improved morphometric parameters. Preservation of inhibitory synaptic terminals was accompanied by significant improvement in the motor as well as in the nociceptive recovery. Overall, the present data suggest that acute repair of neonatal peripheral nerves with fibrin sealant results in neuroprotection and regeneration of motor and sensory axons.

The new heterologous fibrin sealant in combination with low-level laser therapy (LLLT) in the repair of the buccal branch of the facial nerve

This study aimed to evaluate the effects of low-level laser therapy (LLLT) in the repair of the buccal branch of the facial nerve with two surgical techniques: end-to-end epineural suture and coaptation with heterologous fibrin sealant. Forty-two male Wistar rats were randomly divided into five groups: control group (CG) in which the buccal branch of the facial nerve was collected without injury; (2) experimental group with suture (EGS) and experimental group with fibrin (EGF): The buccal branch of the facial nerve was transected on both sides of the face. End-to-end suture was performed on the right side and fibrin sealant on the left side; (3) Experimental group with suture and laser (EGSL) and experimental group with fibrin and laser (EGFL). All animals underwent the same surgical procedures in the EGS and EGF groups, in combination with the application of LLLT (wavelength of 830 nm, 30 mW optical power output of potency, and energy density of 6 J/cm(2)). The animals of the five groups were euthanized at 5 weeks post-surgery and 10 weeks post-surgery. Axonal sprouting was observed in the distal stump of the facial nerve in all experimental groups. The observed morphology was similar to the fibers of the control group, with a predominance of myelinated fibers. In the final period of the experiment, the EGSL presented the closest results to the CG, in all variables measured, except in the axon area. Both surgical techniques analyzed were effective in the treatment of peripheral nerve injuries, where the use of fibrin sealant allowed the manipulation of the nerve stumps without trauma. LLLT exhibited satisfactory results on facial nerve regeneration, being therefore a useful technique to stimulate axonal regeneration process.

Fibrin, the preferred scaffold for cell transplantation after myocardial infarction? An old molecule with a new life

Fibrin is a topical haemostat, sealant and tissue glue, which consists of concentrated fibrinogen and thrombin. It has broad medical and research uses. Recently, several studies have shown that engineered patches comprising mixtures of biological or synthetic materials and progenitor cells showed therapeutic promise for regenerating damaged tissues. In that context, fibrin maintains cell adherence at the site of injury, where cells are required for tissue repair, and offers a nurturing environment that protects implanted cells without interfering with their expected benefit. Here we review the past, present and future uses of fibrin, with a focus on its use as a scaffold material for cardiac repair. Fibrin patches filled with regenerative cells can be placed over the scarring myocardium; this methodology avoids many of the drawbacks of conventional cell-infusion systems. Advantages of using fibrin also include extraction from the patient's blood, an easy readjustment and implantation procedure, increase in viability and early proliferation of delivered cells, and benefits even with the patch alone. In line with this, we discuss the numerous preclinical studies that have used fibrin-cell patches, the practical issues inherent in their generation, and the necessary process of scaling-up from animal models to patients. In the light of the data presented, fibrin stands out as a valuable biomaterial for delivering cells to damaged tissue and for promoting beneficial effects. However, before the fibrin scaffold can be translated from bench to bedside, many issues must be explored further, including suboptimal survival and limited migration of the implanted cells to underlying ischaemic myocardium. Copyright © 2016 John Wiley & Sons, Ltd.

A new heterologous fibrin sealant as a scaffold to cartilage repair-Experimental study and preliminary results

Autologous fibrin gel is commonly used as a scaffold for filling defects in articular cartilage. This biomaterial can also be used as a sealant to control small hemorrhages and is especially helpful in situations where tissue reparation capacity is limited. In particular, fibrin can act as a scaffold for various cell types because it can accommodate cell migration, differentiation, and proliferation. Despite knowledge of the advantages of this biomaterial and mastery of the techniques required for its application, the durability of several types of sealant at the site of injury remains questionable. Due to the importance of such data for evaluating the quality and efficiency of fibrin gel formulations on its use as a scaffold, this study sought to analyze the heterologous fibrin sealant developed from the venom of Crotalus durissus terrificus using studies in ovine experimental models. The fibrin gel developed from the venom of this snake was shown to act as a safe, stable, and durable scaffold for up to seven days, without causing adverse side effects. Fibrin gel produced from the venom of the Crotalus durissus terrificus snake possesses many clinical and surgical uses. It presents the potential to be used as a biomaterial to help repair skin lesions or control bleeding, and it may also be used as a scaffold when applied together with various cell types. The intralesional use of the fibrin gel from the venom of this snake may improve surgical and clinical treatments in addition to being inexpensive and adequately consistent, durable, and stable. The new heterologous fibrin sealant is a scaffold candidate to cartilage repair in this study.