Fibrin and wound healing

The effect of bend relief perforations upon extrinsic graft obstruction risk - a histological analysis

Extrinsic Outflow Graft Obstruction (EOGO) is a potential complication of durable left ventricular assist device (LVAD) therapy characterized by obstructive biodebris accumulation between the outflow graft (OG) and, in the case of HM3, the bend relief (BR). Recent reports have suggested that perforating the HM3 BR may help prevent EOGO. The study objective was to histologically compare the nature and constituency of explanted biologic material from beneath intact HM3 BRs (n = 7; with n = 3 EOGO) beneath perforated HM3 BRs (n = 5), and outside the BR (n = 2). Results indicate that material beneath intact BRs (EOGO and non-EOGO samples) is consistently acellular protein (fibrin) or biodebris while material beneath perforated BRs demonstrated collagen and cell infiltration through the perforations, resembling the material found outside the graft beyond the BR where EOGO is not observed. Despite the small sample size, this study provides a hypothetical mechanism(s) underlying potential benefits of BR perforations in preventing EOGO by attenuating biodebris accumulation through collagen and cell infiltration.

The effectiveness of concentrated growth factor in facial nerve crush injury

AIM

To evaluate the effect of concentrated growth factor (CGF) on regeneration of facial nerve after crush injury.

MATERIALS AND METHODS

Fourteen rats were randomized into two groups. The control group (CG) (n = 7) received a crush injury to the right facial nerve. The CGF group (CGFG) (n = 7) received a crush injury to the right facial nerve and concentrated growth factor prepared from their own blood thereafter. Left facial nerves were used for functional comparison. Nerve function was evaluated using whisker movements and electromyography. Histologic properties were evaluated using hematoxylin and eosin and Masson-trichrome staining, and immunohistochemical properties were evaluated using Neurofilament-H and Anti-Tau degeneration markers.

RESULTS

In the CGFG, whisker functions began to recover earlier and recovered more quickly compared with the CG. The CG showed significantly prolonged latency and reduced amplitudes in the first week compared with the CGFG (p < 0.05). Recordings of 4th-week latency and amplitudes were similar to the preoperative period in the CGFG (p > 0.05), whereas recordings of the same week were significantly worse in the CG (p < 0.05). Edema and fibrosis were also more pronounced in the CG compared with the CGFG. Neurofilament-H and Anti-Tau were at significantly high levels in the CG (p < 0.05).

CONCLUSION

Concentrated growth factor promotes recovery in facial crush injury and may prove a cost-effective, practical, and effective treatment choice in peripheral nerve injury.

Differences between first- and second-generation autologous platelet concentrates

Autologous platelet concentrates (APCs) applied alone or combined with other biomaterials are popular bioactive factors employed in regenerative medicine. The main biological rationale of using such products is to concentrate blood-derived growth factors and cells into the wound microenvironment to enhance the body's natural healing capacity. First-generation APC is represented by platelet-rich plasma (PRP). While different protocols have been documented for PRP preparation, they overall consist of two cycles of centrifugation and have important limitations related to the use of an anticoagulant first and an activator afterward, which may interfere with the natural healing process and the release of bioactive molecules. The second generation of platelet concentrates is represented by leukocyte and platelet-rich fibrin (L-PRF). L-PRF protocols involve a single centrifugation cycle and do not require the use of anticoagulants and activators, which makes the preparation more straight forward, less expensive, and eliminates potential risks associated with the use of activators. However, since no anticoagulant is employed, blood undergoes rapid clotting within the blood collection tube; hence, a timely management of L-PRF is crucial. This review provides an overview on the most documented protocols for APC preparations and critically discusses the main differences between first- and second-generation APCs in terms of cell content, protein release, and the formation of a 3D fibrin network. It appears evident that the inconsistency in reporting protocol parameters by most studies has contributed to conflicting conclusions regarding the efficacy of different APC formulations and has significantly limited the ability to interpret the results of individual clinical studies. In the future, the use of a standardized classification system, together with a detailed reporting on APC protocol parameters is warranted to make study outcomes comparable. This will also allow to clarify important aspects on the mechanism of action of APCs (like the role of leukocytes and centrifugation parameters) and to optimize the use of APCs in regenerative medicine.

Identification of Amino Acid Residues Critical for the Interaction of Fibrin with N-Cadherin

We recently identified N-cadherin as a novel receptor for fibrin and localized complementary binding sites within the fibrin βN-domains and the third and fifth extracellular domains (EC3 and EC5) of N-cadherin. We also hypothesized that the His16 and Arg17 residues of the βN-domains and the (Asp/Glu)-X-(Asp/Glu) motifs present in the EC3 and EC5 domains may play roles in the interaction between fibrin and N-cadherin. The primary objectives of this study were to test these hypotheses and to further clarify the structural basis for this interaction. To test our hypotheses, we first mutated His16 and Arg17 in the recombinant (β15-66)2 fragment, which mimics the dimeric arrangement of the βN-domains in fibrin, using site-directed mutagenesis. The results revealed that the mutations of both His16 and Arg17 are critical for the interaction. Next, we mutated Asp/Glu residues in the three (Asp/Glu)-X-(Asp/Glu) motifs, M1 (Asp-Phe-Glu), M2 (Glu-Ala-Glu), and M3 (Asp-Tyr-Asp), of the fibrin-binding N-cad(3-5) fragment of N-cadherin. The results showed that Asp292 and Glu294 of M1, and Asp468 and Asp470 of M3, are critical for the interaction. Our molecular modeling of the 3D structure of the EC3-EC4-EC5 domains revealed that these residues are located at the interfaces of EC3-EC4 and EC4-EC5 and that some may also be involved in calcium binding. In conclusion, our study identified amino acid residues in the fibrin βN-domains and the EC3 and EC5 domains of N-cadherin that are critical for the interaction of fibrin with N-cadherin and localized the fibrin-binding residues in the 3D structure of N-cadherin.

A Versatile Skin-Derived Extracellular Matrix Hydrogel-Based Platform to Investigate the Function of a Mechanically Isolated Adipose Tissue Stromal Vascular Fraction

Introduction: To accelerate cutaneous wound healing and prevent scarring, regenerative approaches such as injecting a mechanically derived tissue stromal vascular fraction (tSVF) are currently under clinical and laboratory investigations. The aim of our study was to investigate a platform to assess the interaction between skin-derived extracellular matrix (ECM) hydrogels and tSVF and their effects on their microenvironment in the first ten days of culture. Material and Methods: A tSVF mixed with ECM hydrogel was cultured for ten days. After 0, 3, 5, and 10 days of culture viability, histology, immunohistochemistry, gene expression, and collagen alignment and organization were assessed. Results: The viability analysis showed that tSVF remained viable during 10 days of culture and seemed to remain within their constitutive ECM. The fiber analysis demonstrated that collagen alignment and organization were not altered. No outgrowth of capillaries was observed in (immuno)histochemical staining. The gene expression analysis revealed that paracrine factors TGFB1 and VEGFA did not change and yet were constitutively expressed. Pro-inflammatory factors IL1B and IL6 were downregulated. Matrix remodeling gene MMP1 was upregulated from day three on, while MMP14 was upregulated at day three and ten. Interestingly, MMP14 was downregulated at day five compared to day three while MMP2 was downregulated after day zero. Conclusions: Skin-derived ECM hydrogels appear to be a versatile platform for investigating the function of a mechanically isolated adipose tissue stromal vascular fraction. In vitro tSVF remained viable for 10 days and sustained the expression of pro-regenerative factors, but is in need of additional triggers to induce vascularization or show signs of remodeling of the surrounding ECM. In the future, ECM-encapsulated tSVF may show promise for clinical administration to improve wound healing.

Surgical Evaluation of Autologous Platelet-rich Fibrin Membrane as a Coverage Layer in Repair of Urethrocutaneous Fistula after Hypospadias Surgeries: A Randomized Controlled Trial

Purpose

It has recently been reported that the use of platelet-rich fibrin (PRF) as an extralayer over the urethroplasty has been related to a considerable reduction in fistula rates. Due to the lack of evidence supporting the usage of PRF in urethrocutaneous fistula (UCF) repair, we conducted this study to evaluate the efficacy of PRF in patients with UCF.

Materials and Methods

We conducted a randomized controlled study on patients with distal fistula after hypospadias repair. Patients were randomized into two groups, one with local dartos coverage and the other with PRF coverage layer.

Results

In the present study, we included 37 patients; 20 patients underwent local dartos coverage, and 17 patients underwent PRF. The mean age was 22.45 ± 4545 ± 4515 ± ±15.35 (range 11-56) months for the study group and 20.6 ± 66 ± 614 ± ±14.5 (range 6-45) months for the control group. The incidence of recurrent UCF was 11.8% in the treatment group (two patients), whereas the incidence was 30% (six patients) in the control group (P = 0.246).

Conclusion

UCF surgery may benefit from the use of PRF as a supportive tissue that promotes wound healing, angiogenesis, and tissue restoration. We believe that the use of PRF as a new approach for UCF repair should be investigated further through clinical studies.

Effects of Platelet-Rich Plasma and Concentrated Growth Factor on Viability of Ultra-Diced Cartilage Grafts in a Rabbit Model

BACKGROUND

Although rhinoplastic surgery has progressed considerably in recent years, nasal dorsal irregularities still cause postoperative distress for both surgeons and patients.

PURPOSE

The aim of this study was to measure the association between two biologic graft adjuncts, platelet-rich plasma (PRP) and concentrated growth factor (CGF), and ultra-diced cartilage viability in an animal model.

STUDY DESIGN, SETTING, AND SAMPLE

This study was designed as a randomized in-vivo study using a rabbit model. Fourteen rabbits were utilized in this investigation. The ultra-diced cartilage was obtained from auricular cartilage.

PREDICTOR VARIABLE

The graft biologic adjunct is the predictor variable. There were three treatment groups: graft mixed with PRP or CGF or untreated (control). The grafts were placed in three separate pockets opened on the same rabbit. Grafts were harvested 3 months after insertion for analysis.

MAIN OUTCOME VARIABLE(S)

The primary outcome variable was histopathological and regenerative scores obtained from multiple histopathological parameters indicating the viability of the cartilage. Histopathological score parameters were chondrocyte loss, inflammation, fibrosis, cartilage fragmentation, and calcified area formations in the lacunae. Regenerative score parameters were peripheral cell proliferation in the cartilage tissue, vascularization in the connective tissue, proteoglycan increase in the matrix, and the amount of connective tissue.

COVARIATES

The variables were age, sex, and weight.

ANALYSES

Statistical analysis employed the analysis of variance test, with a significance level of P < .05.

RESULTS

The sample was composed of 14 rabbits and 42 samples. The histopathologic scores were 11.93 (±2.49), 8.78 (±2.19), and 6.85 (±1.46) for the control, PRP, and CGF groups, respectively. A statistically significant difference was found in the PRP (P < .0275) and CGF (P < .0001) groups compared to the control group. The regenerative scores were 6.21 (±0.97), 8.85 (±1.70), and 12.07 (±1.26) for the control, PRP and CGF groups, respectively. A statistically significant difference was found in the PRP (P < .0159) and CGF (P < .0001) groups compared to the control group.

CONCLUSION AND RELEVANCE

This is the first study investigating the ultra-diced cartilage graft in an experimental animal model. Histopathological examination has shown that mixing ultra-diced cartilage with CGF or PRP increases viability by reducing the histopathological score and increasing the regenerative score.

Successful Management of an Extensive Class V Carious Lesion With Dehiscence and Loss of the Attachment Apparatus: A Case Report With Six-Month Follow-Up

The present case report presents a rare instance of a Class V carious lesion combined with alveolar dehiscence in a non-vital maxillary central incisor without gingival recession. A 25-year-old male exhibited symptoms, including a blackened tooth (#21), pus discharge, and tenderness, with clinical examination revealing a Class V carious lesion and partial dehiscence of the labial cortical plate, confirmed by radiographic and cone-beam computed tomography (CBCT) imaging. Treatment involved a two-phase approach: endodontic therapy with root canal instrumentation and obturation using a bioceramic sealer, followed by surgical intervention that included carious lesion removal, restoration with resin-modified glass ionomer cement (RMGIC), and application of a platelet-rich fibrin (PRF) membrane. PRF was selected for its regenerative properties, promoting bone healing and tissue repair, and was particularly beneficial in extensive lesions. Post-treatment follow-up at six months demonstrated complete soft tissue healing, reduced probing depth, and significant bone regeneration. This case illustrates the effective management of a complex dental condition through a combined endodontic and periodontal approach enhanced by PRF therapy, yielding favorable clinical and radiographic outcomes.

Extracellular matrix-inspired biomaterials for wound healing

Diabetic foot ulcers (DFU) are a debilitating and life-threatening complication of Diabetes Mellitus. Ulceration develops from a combination of associated diabetic complications, including neuropathy, circulatory dysfunction, and repetitive trauma, and they affect approximately 19-34% of patients as a result. The severity and chronic nature of diabetic foot ulcers stems from the disruption to normal wound healing, as a result of the molecular mechanisms which underly diabetic pathophysiology. The current standard-of-care is clinically insufficient to promote healing for many DFU patients, resulting in a high frequency of recurrence and limb amputations. Biomaterial dressings, and in particular those derived from the extracellular matrix (ECM), have emerged as a promising approach for the treatment of DFU. By providing a template for cell infiltration and skin regeneration, ECM-derived biomaterials offer great hope as a treatment for DFU. A range of approaches exist for the development of ECM-derived biomaterials, including the use of purified ECM components, decellularisation and processing of donor/ animal tissues, or the use of in vitro-deposited ECM. This review discusses the development and assessment of ECM-derived biomaterials for the treatment of chronic wounds, as well as the mechanisms of action through which ECM-derived biomaterials stimulate wound healing.

The effect of platelet-rich fibrin, platelet-rich plasma, and concentrated growth factor in the repair of full thickness rotator cuff tears

BACKGROUND

Rotator cuff lesions rank among the prevalent causes of shoulder pain. Combining surgical interventions with growth factors, scaffolds, and stem cell therapies can effectively decrease the likelihood of rotator cuff repair recurrence. Platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and concentrated growth factor (CGF), isolated from blood and rich in growth factors, have a critical role in cell migration, cell proliferation, and angiogenesis during the tissue regeneration process. Investigations have further substantiated the beneficial impact of PRP and PRF on the biomechanical and histologic attributes of the tendon-bone interface. We aimed to investigate the effectiveness of CGF compared with PRF and PRP in the repair of rotator cuff lesions as a new treatment strategy.

METHODS

Incision was performed on both shoulder regions of 21 adult rabbits. After 8 weeks, both shoulders of the rabbits were repaired by suturing. PRF and CGF were administered to 2 separate groups along with the repair. Tissues were collected for biomechanical measurements and histologic evaluations.

RESULTS

Histologically, CGF, PRF, and PRP showed similar results to the healthy control group. The level of improvement was significant in the PRF and PRP groups. In the PRF group, the distribution of Ki67 (+), CD31 (+), and CD34 (+) cells was determined intensely in the tendon-bone junction regions. Apoptotic cells increased significantly in the repair group compared with the healthy group, whereas fewer apoptotic cells were found in the PRF-, PRP-, and CGF-applied groups. In the biomechanical results, no statistical difference was recorded among the groups.

CONCLUSION

The use of PRF, PRP, and CGF in rotator cuff repair shows promise in shortening the treatment period and preventing the recurrence of rotator cuff lesions.

Deciphering the crosstalk between inflammation and biofilm in chronic wound healing: Phytocompounds loaded bionanomaterials as therapeutics

In terms of the economics and public health, chronic wounds exert a significant detrimental impact on the health care system. Bacterial infections, which cause the formation of highly resistant biofilms that elude standard antibiotics, are the main cause of chronic, non-healing wounds. Numerous studies have shown that phytochemicals are effective in treating a variety of diseases, and traditional medicinal plants often include important chemical groups such alkaloids, phenolics, tannins, terpenes, steroids, flavonoids, glycosides, and fatty acids. These substances are essential for scavenging free radicals which helps in reducing inflammation, fending off infections, and hastening the healing of wounds. Bacterial species can survive in chronic wound conditions because biofilms employ quorum sensing as a communication technique which regulates the expression of virulence components. Fortunately, several phytochemicals have anti-QS characteristics that efficiently block QS pathways, prevent drug-resistant strains, and reduce biofilm development in chronic wounds. This review emphasizes the potential of phytocompounds as crucial agents for alleviating bacterial infections and promoting wound healing by reducing the inflammation in chronic wounds, exhibiting potential avenues for future therapeutic approaches to mitigate the healthcare burden provided by these challenging conditions.

Thrombin and Thrombin-Incorporated Biomaterials for Disease Treatments

Thrombin, a coagulation-inducing protease, has long been used in the hemostatic field. During the past decades, many other therapeutic uses of thrombin have been developed. For instance, burn treatment, pseudoaneurysm therapy, wound management, and tumor vascular infarction (or tumor vasculature blockade therapy) can all utilize the unique and powerful function of thrombin. Based on their therapeutic effects, many thrombin-associated products have been certificated by the Food and Drug Administration, including bovine thrombin, human thrombin, recombinant thrombin, fibrin glue, etc. Besides, several thrombin-based drugs are currently undergoing clinical trials. In this article, the therapeutic uses of thrombin (from the initial hemostasis to the latest cancer therapy), the commercially available drugs associated with thrombin, and the pros and cons of thrombin-based therapeutics (e.g., adverse immune responses related to bovine thrombin, thromboinflammation, and vasculogenic "rebounds") are summarized. Further, the current challenges and possible future research directions of thrombin-incorporated biomaterials and therapies are discussed. It is hoped that this review may provide a valuable reference for researchers in this field and help them to design safer and more effective thrombin-based drugs for fighting against various intractable diseases.

Use of Concentrated Growth Factor (CGF) in Prosthetic-Guided Reconstruction on Two-Wall Bone Defect after Cystectomy: An Alternative to Traditional Regeneration

This clinical case report's objective was to describe an alternative technique executed to ensure bone regeneration after removing a cystic lesion in the upper jaw. The bone defect after the cystectomy was filled with autologous fibrin-rich clots containing concentrated growth factor (CGF). A 45-year-old female patient was presumed to have a cystic lesion with massive bone destruction on the vestibular and palatal walls between teeth 2.2 and 2.3. CGF was applied to fill the gap to promote the development of the bone. The tooth was asymptomatic and repair was still increasing steadily after a year, according to the results of the clinical and radiological follow-up assessment. This article describes a different way to treat a two-wall defect involving both the palatal and buccal bone, after removing a cystic lesion, with the use of CGF as an equivalent to the traditional use of autologous or heterologous bone. A promising substance for bone repair is CGF fibrin, which may encourage the growth of new bone in jaw deformities and promote bone tissue healing.

Identification of Neural (N)-Cadherin as a Novel Endothelial Cell Receptor for Fibrin and Localization of the Complementary Binding Sites

Based on the high structural homology between vascular endothelial (VE)-cadherin and neural (N)-cadherin, we hypothesized that fibrin, which is known to interact with VE-cadherin and promote angiogenesis through this interaction, may also interact with N-cadherin. To test this hypothesis, we prepared fibrin and its plasmin-produced and recombinant fragments covering practically all parts of the fibrin molecule. We also prepared the soluble extracellular portion of N-cadherin (sN-cadherin), which includes all five extracellular N-cadherin domains, and studied its interaction with fibrinogen, fibrin, and the aforementioned fibrin fragments using two independent methods, ELISA and SPR. The experiments confirmed our hypothesis, revealing that fibrin interacts with sN-cadherin with high affinity. Furthermore, the experiments localized the N-cadherin binding site within the fibrin βN-domains. Notably, the recombinant dimeric (β15-66)2 fragment, corresponding to these domains and mimicking their dimeric arrangement in fibrin, preserved the N-cadherin-binding properties of fibrin. To localize the fibrin binding site within N-cadherin, we performed ELISA and SPR experiments with (β15-66)2 and recombinant N-cadherin fragments representing its individual extracellular domains and combinations thereof. The results obtained indicate that the interaction of fibrin with N-cadherin occurs through the third and fifth extracellular domains of the latter. This is in contrast to our previous study, which revealed that fibrin interacts only with the third extracellular domain of VE-cadherin. In conclusion, our study identified N-cadherin as a novel receptor for fibrin and localized complementary binding sites within both fibrin and N-cadherin. The pathophysiological role of this interaction remains to be established.

Medicinal Plants in the Treatment of Myocardial Infarction Disease: A Systematic Review

BACKGROUND

Myocardial infarction (MI), also referred to as a "heart attack," is brought on by a partial or total interruption of blood supply to the myocardium. Myocardial infarction can be "silent," go undiagnosed, or it can be a catastrophic occurrence that results in hemodynamic decline and untimely death. In recent years, herbal remedies for MI have become effective, secure, and readily accessible.

OBJECTIVE

The purpose of this review was to examine the medicinal plants and phytochemicals that have been used to treat MI in order to assess the potential contribution of natural substances to the development of herbal MI treatments.

METHODOLOGY

A literature search was employed to find information utilizing electronic databases, such as Web of Science, Google Scholar, PubMed, Sci Finder, Reaxys, and Cochrane.

RESULTS

The identification of 140 plants from 12 families led to the abstraction of data on the plant families, parts of the plant employed, chemical contents, extracts, model used, and dose.

CONCLUSION

The majority of the MI plants, according to the data, belonged to the Fabaceae (11%) and Asteraceae (9%) families, and the most prevalent natural components in plants with MI were flavonoids (43%), glucosides (25%), alkaloids (23%), phenolic acid (19%), saponins (15%), and tannins (12%).

A Split-Face Study to Evaluate Efficacy of Autologous Injectable Platelet-Rich Fibrin With Microneedling Against Microneedling With Normal Saline (Placebo Control) in Atrophic Acne Scars

BACKGROUND

Acne scars cause significant psychosocial stress. Despite a wide armamentarium, there is a constant search for an effective modality. Autologous injectable platelet-rich fibrin (i-PRF) is a promising novel option in the management of atrophic scars.

OBJECTIVE

To compare efficacy of autologous i-PRF with microneedling against microneedling alone in atrophic acne scars.

MATERIALS AND METHODS

A split-face prospective interventional study was conducted on 40 patients with atrophic acne scars. Autologous i-PRF and normal saline were injected into each scar on right (study) and left (control) sides, respectively, followed by microneedling on both sides. Four sessions were performed at monthly intervals with follow-up at 2 months. For assessment, Goodman and Baron (GB) scale, physician subjective score, and patient satisfaction scores were used.

RESULTS

Mean baseline GB grade on each side was 3.45. At 24 weeks, mean GB grade was significantly reduced on the study side (1.47, SD 0.56) than control side (3.33, SD 0.53). Mean patient satisfaction score was significantly higher on the right side (5.95) compared with the left side (5.35). Rolling scars responded the best followed by boxcar and ice-pick scars.

CONCLUSION

Autologous i-PRF and microneedling act synergistically to improve acne scars.

Fit and forget: The future of dental implant therapy via nanotechnology

Unlike orthopedic implants, dental implants require the orchestration of both osseointegration at the bone-implant interface and soft-tissue integration at the transmucosal region in a complex oral micro-environment with ubiquitous pathogenic bacteria. This represents a very challenging environment for early acceptance and long-term survival of dental implants, especially in compromised patient conditions, including aged, smoking and diabetic patients. Enabling advanced local therapy from the surface of titanium-based dental implants via novel nano-engineering strategies is emerging. This includes anodized nano-engineered implants eluting growth factors, antibiotics, therapeutic nanoparticles and biopolymers to achieve maximum localized therapeutic action. An important criterion is balancing bioactivity enhancement and therapy (like bactericidal efficacy) without causing cytotoxicity. Critical research gaps still need to be addressed to enable the clinical translation of these therapeutic dental implants. This review informs the latest developments, challenges and future directions in this domain to enable the successful fabrication of clinically-translatable therapeutic dental implants that would allow for long-term success, even in compromised patient conditions.

Maxillary Sinus Augmentation Using Autologous Platelet Concentrates (Platelet-Rich Plasma, Platelet-Rich Fibrin, and Concentrated Growth Factor) Combined with Bone Graft: A Systematic Review

BACKGROUND

The current review aims to provide an overview of the most recent research on the potentials of concentrated growth factors used in the maxillary sinus lift technique.

MATERIALS AND METHODS

"PRP", "PRF", "L-PRF", "CGF", "oral surgery", "sticky bone", "sinus lift" were the search terms utilized in the databases Scopus, Web of Science, and Pubmed, with the Boolean operator "AND" and "OR".

RESULTS

Of these 1534 studies, 22 publications were included for this review.

DISCUSSION

The autologous growth factors released from platelet concentrates can help to promote bone remodeling and cell proliferation, and the application of platelet concentrates appears to reduce the amount of autologous bone required during regenerative surgery. Many authors agree that growth factors considerably enhance early vascularization in bone grafts and have a significantly positive pro-angiogenic influence in vivo when combined with alloplastic and xenogeneic materials, reducing inflammation and postoperative pain and stimulating the regeneration of injured tissues and accelerating their healing.

CONCLUSIONS

Even if further studies are still needed, the use of autologous platelet concentrates can improve clinical results where a large elevation of the sinus is needed by improving bone height, thickness and vascularization of surgical sites, and post-operative healing.

The extracellular matrix of dystrophic mouse diaphragm accounts for the majority of its passive stiffness and is resistant to collagenase digestion

The healthy skeletal muscle extracellular matrix (ECM) has several functions including providing structural integrity to myofibers, enabling lateral force transmission, and contributing to overall passive mechanical properties. In diseases such as Duchenne Muscular dystrophy, there is accumulation of ECM materials, primarily collagen, which results in fibrosis. Previous studies have shown that fibrotic muscle is often stiffer than healthy muscle, in part due to the increased number and altered architecture of collagen fibers within the ECM. This would imply that the fibrotic matrix is stiffer than the healthy matrix. However, while previous studies have attempted to quantify the extracellular contribution to passive stiffness in muscle, the outcomes are dependent on the type of method used. Thus, the goals of this study were to compare the stiffness of healthy and fibrotic muscle ECM and to demonstrate the efficacy of two methods for quantifying extracellular-based stiffness in muscle, namely decellularization and collagenase digestion. These methods have been demonstrated to remove the muscle fibers or ablate collagen fiber integrity, respectively, while maintaining the contents of the extracellular matrix. Using these methods in conjunction with mechanical testing on wildtype and D2.mdx mice, we found that a majority of passive stiffness in the diaphragm is dependent on the ECM, and the D2.mdx diaphragm ECM is resistant to digestion by bacterial collagenase. We propose that this resistance is due to the increased collagen cross-links and collagen packing density in the ECM of the D2.mdx diaphragm. Taken altogether, while we did not find increased stiffness of the fibrotic ECM, we did observe that the D2.mdx diaphragm conveyed resistance against collagenase digestion. These findings demonstrate how different methods for measuring ECM-based stiffness each have their own limitations and can produce different results.

Alveolar ridge preservation in post-extraction sockets using concentrated growth factors: a split-mouth, randomized, controlled clinical trial

Aim

The aim of this clinical trial was to assess the impact of autologous concentrated growth factor (CGF) as a socket-filling material and its ridge preservation properties following the lower third molar extraction.

Materials and methods

A total of 60 sides of 30 participants who had completely symmetrical bilateral impacted lower third molars were enrolled. The primary outcome variables of the study were bone height and width, bone density, and socket surface area in the coronal section. Cone beam computed tomography images were obtained immediately after surgery and three months after surgery as a temporal measure. Follow-up data were compared to the baseline using paired and unpaired t-tests.

Results

CGF sites had higher values in height and width when compared to control sites (Buccal wall 32.9 ± 3.5 vs 29.4 ± 4.3 mm, Lingual wall 25.4 ± 3.5 vs 23.1 ± 4 mm, and Alveolar bone width 21.07 ± 1.55vs19.53 ± 1.90 mm, respectively). Bone density showed significantly higher values in CGF sites than in control sites (Coronal half 200 ± 127.3 vs -84.1 ± 121.3 and Apical half 406.5 ± 103 vs 64.2 ± 158.6, respectively). There was a significant difference between both sites in the reduction of the periodontal pockets.

Conclusion

CGF application following surgical extraction provides an easy, low-cost, and efficient option for alveolar ridge preservation. Thus, the use of CGF by dentists during dental extractions may be encouraged, particularly when alveolar ridge preservation is required.

Clinical trial registration

TCTR identification, TCTR20221028003.

General overview of biopolymers: structure and properties

Biopolymers are synthesized from a biological origin under natural phenomenon especially during their growth cycle, in the form of polymeric substances that portrays excellent properties such as flexibility, tensile strength, steadiness, reusability, and so on. The amalgamated form of two or more biopolymers leads to the formation of “biocomposites” with novel applications. Several mechanisms were identified for the effective production of biopolymers from diverse life forms such as microbial origin plant and animal origin. Based on their origin, biopolymer differs in their structure and functions. Biopolymers are preferred over chemically synthesized polymers due to their biodegradability and their impact on the environment. Biopolymers play a pivotal role in pharmaceutical industries. The biopolymers could be employed for, the administration of medicine as well as regenerative medicine to reach minimal immunogenicity and maximum pharmacological expressivity in a treated individual. Based on their properties biopolymers were exclusively used in medical devices, cosmaceuticals, and confectionaries, it is also used as additives in food industries, bio-sensors, textile industries, and wastewater treatment plants. Ecological support is of utmost concern nowadays due to the ever-expanding ramification over the planet by usage of plastic as packaging material, turning up scientists and researchers to focus on biodegradable biopolymer utilization. The miscibility-structural-property relation between every biopolymer must be focused on to improve the better environment. Specific biopolymers are designed for the betterment of agrarian and commoners of society. Advanced structural modifications, properties of biopolymers, and applications of biopolymers to achieve a greener environment were discussed in this chapter.

A comparative high-resolution physicochemical analysis of commercially available fibrin sealants: Impact of sealant osmolality on biological performance

Fibrin sealants are well-established components of the surgical toolbox, especially in procedures that harbor a high risk of perioperative bleeding. Their widespread use as hemostats, sealants or tissue-adhesives in various surgical settings has shown that the choice of the appropriate sealant system affects the clinical outcome. While many studies have compared the hemostatic efficiency of fibrin sealants to that of other natural or synthetic sealants, there is still limited data on how subtle differences in fibrin sealant formulations relate to their biological performance. Here, we performed an in-depth physicochemical and biological characterization of the two most commonly used fibrin sealants in the US and Europe: TISSEEL™ ("FS") and VISTASEAL™/VERASEAL™ ("FS+Osm"). Our chemical analyses demonstrated differences between the two sealants, with lower fibrinogen concentrations and supraphysiological osmolality in the FS+Osm formulation. Rheological testing revealed FS clots have greater clot stiffness, which strongly correlated with network density. Ultrastructural analysis by scanning electron microscopy revealed differences between FS and FS+Osm fibrin networks, the latter characterized by a largely amorphous hydrogel structure in contrast to the physiological fibrillar network of FS. Cytocompatibility experiments with human fibroblasts seeded on FS and FS+Osm fibrin networks, or cultured in presence of sealant extracts, revealed that FS+Osm induced apoptosis, which was not observed with FS. Although differential sealant osmolality and amounts of fibrinogen, as well as the presence of Factor XIII or additives such as antifibrinolytics, may explain the mechanical and structural differences observed between the two fibrin sealants, none of these substances are known to cause apoptosis at the respective concentrations in the sealant formulation. We thus conclude that hyper osmolality in the FS+Osm formulation is the primary trigger of apoptosis-a mechanism that should be evaluated in more detail, as it may affect the cellular wound healing response in situ.

Ischemia Impaired Wound Healing Model in the Rat—Demonstrating Its Ability to Test Proangiogenic Factors

Chronic wounds remain a serious clinical problem with insufficient therapeutic approaches. In this study we investigated the dose dependency of rhVEGF165 in fibrin sealant in both ischemic and non-ischemic excision wounds using our recently developed impaired-wound healing model. An abdominal flap was harvested from the rat with unilateral ligation of the epigastric bundle and consequent unilateral flap ischemia. Two excisional wounds were set in the ischemic and non-ischemic area. Wounds were treated with three different rhVEGF165 doses (10, 50 and 100 ng) mixed with fibrin or fibrin alone. Control animals received no therapy. Laser Doppler imaging (LDI) and immunohistochemistry were performed to verify ischemia and angiogenesis. Wound size was monitored with computed planimetric analysis. LDI revealed insufficient tissue perfusion in all groups. Planimetric analysis showed slower wound healing in the ischemic area in all groups. Wound healing was fastest with fibrin treatment—irrespective of tissue vitality. Lower dose VEGF (10 and 50 ng) led to faster wound healing compared to high-dose VEGF. Immunohistochemistry showed the highest vessel numbers in low-dose VEGF groups. In our previously established model, different rhVEGF165 treatments led to dose-dependent differences in angiogenesis and wound healing, but the fastest wound closure was achieved with fibrin matrix alone.

Molecular hydrogen promotes wound healing by inducing early epidermal stem cell proliferation and extracellular matrix deposition

BACKGROUND

Despite progress in developing wound care strategies, there is currently no treatment that promotes the self-tissue repair capabilities. H₂ has been shown to effectively protect cells and tissues from oxidative and inflammatory damage. While comprehensive effects and how H₂ functions in wound healing remains unknown, especially for the link between H₂ and extracellular matrix (ECM) deposition and epidermal stem cells (EpSCs) activation.

METHODS

Here, we established a cutaneous aseptic wound model and applied a high concentration of H₂ (66% H₂) in a treatment chamber. Molecular mechanisms and the effects of healing were evaluated by gene functional enrichment analysis, digital spatial profiler analysis, blood perfusion/oxygen detection assay, in vitro tube formation assay, enzyme-linked immunosorbent assay, immunofluorescent staining, non-targeted metabonomic analysis, flow cytometry, transmission electron microscope, and live-cell imaging.

RESULTS

We revealed that a high concentration of H₂ (66% H₂) greatly increased the healing rate (3 times higher than the control group) on day 11 post-wounding. The effect was not dependent on O₂ or anti-reactive oxygen species functions. Histological and cellular experiments proved the fast re-epithelialization in the H₂ group. ECM components early (3 days post-wounding) deposition were found in the H₂ group of the proximal wound, especially for the dermal col-I, epidermal col-III, and dermis-epidermis-junction col-XVII. H₂ accelerated early autologous EpSCs proliferation (1-2 days in advance) and then differentiation into myoepithelial cells. These epidermal myoepithelial cells could further contribute to ECM deposition. Other beneficial outcomes include sustained moist healing, greater vascularization, less T-helper-1 and T-helper-17 cell-related systemic inflammation, and better tissue remodelling.

CONCLUSION

We have discovered a novel pattern of wound healing induced by molecular hydrogen treatment. This is the first time to reveal the direct link between H₂ and ECM deposition and EpSCs activation. These H₂-induced multiple advantages in healing may be related to the enhancement of cell viability in various cells and the maintenance of mitochondrial functions at a basic level in the biological processes of life.

Nanomaterials and nanomaterials-based drug delivery to promote cutaneous wound healing

Various factors could damage the structure and integrity of skin to cause wounds. Nonhealing or chronic wounds seriously affect the well-being of patients and bring heavy burdens to the society. The past few decades have witnessed application of numerous nanomaterials to promote wound healing. Owing to the unique physicochemical characteristics at nanoscale, nanomaterials-based therapy has been regarded as a potential approach to promote wound healing. In this review, we first overview the wound categories, wound healing process and critical influencing factors. Then applications of nanomaterials with intrinsic therapeutic effect and nanomaterials-based drug delivery systems to promote wound healing are addressed in detail. Finally, current limitations and future perspectives of nanomaterials in wound healing are discussed.

Extensive and Persistent Extravascular Dermal Fibrin Deposition Characterizes Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by progressive multiorgan fibrosis. While the cause of SSc remains unknown, a perturbed vasculature is considered a critical early step in the pathogenesis. Using fibrinogen as a marker of vascular leakage, we found extensive extravascular fibrinogen deposition in the dermis of both limited and diffuse systemic sclerosis disease, and it was present in both early and late-stage patients. Based on a timed series of excision wounds, retention on the fibrin deposit of the splice variant domain, fibrinogen αEC, indicated a recent event, while fibrin networks lacking the αEC domain were older. Application of this timing tool to SSc revealed considerable heterogeneity in αEC domain distribution providing unique insight into disease activity. Intriguingly, the fibrinogen-αEC domain also accumulated in macrophages. These observations indicate that systemic sclerosis is characterized by ongoing vascular leakage resulting in extensive interstitial fibrin deposition that is either continually replenished and/or there is impaired fibrin clearance. Unresolved fibrin deposition might then incite chronic tissue remodeling.

Technological advances in fibrin for tissue engineering

Fibrin is a promising natural polymer that is widely used for diverse applications, such as hemostatic glue, carrier for drug and cell delivery, and matrix for tissue engineering. Despite the significant advances in the use of fibrin for bioengineering and biomedical applications, some of its characteristics must be improved for suitability for general use. For example, fibrin hydrogels tend to shrink and degrade quickly after polymerization, particularly when they contain embedded cells. In addition, their poor mechanical properties and batch-to-batch variability affect their handling, long-term stability, standardization, and reliability. One of the most widely used approaches to improve their properties has been modification of the structure and composition of fibrin hydrogels. In this review, recent advances in composite fibrin scaffolds, chemically modified fibrin hydrogels, interpenetrated polymer network (IPN) hydrogels composed of fibrin and other synthetic or natural polymers are critically reviewed, focusing on their use for tissue engineering.

Fibrinolysis Regulation: A Promising Approach to Promote Osteogenesis

Soon after bone fracture, the initiation of the coagulation cascade results in the formation of a blood clot, which acts as a natural material to facilitate cell migration and osteogenic differentiation at the fracture site. The existence of hematoma is important in early stage of bone healing, but the persistence of hematoma is considered harmful for bone regeneration. Fibrinolysis is recently regarded as a period of critical transition in angiogenic-osteogenic coupling, it thereby is vital for the complete healing of the bone. Moreover, the enhanced fibrinolysis is proposed to boost bone regeneration through promoting the formation of blood vessels, and fibrinolysis system as well as the products of fibrinolysis also play crucial roles in the bone healing process. Therefore, the purpose of this review is to elucidate the fibrinolysis-derived effects on osteogenesis and summarize the potential approaches-improving bone healing by regulating fibrinolysis, with the purpose to further understand the integral roles of fibrinolysis in bone regeneration and to provide theoretical knowledge for potential fibrinolysis-related osteogenesis strategies. Impact statement Fibrinolysis emerging as a new and viable therapeutic intervention to be contained within osteogenesis strategies, however to now, there have been no review articles which collates the information between fibrinolysis and osteogenesis. This review, therefore, focusses on the effects that fibrinolysis exerts on bone healing, with a purpose to provide theoretical reference to develop new strategies to modulate fibrinolysis to accelerate fibrinolysis thus enhancing bone healing.

Intact Fish Skin Graft vs. Standard of Care in Patients with Neuroischaemic Diabetic Foot Ulcers (KereFish Study): An International, Multicentre, Double-Blind, Randomised, Controlled Trial Study Design and Rationale

BACKGROUND

Cell and/or tissue-based wound care products have slowly advanced in the treatment of non-healing ulcers, however, few studies have evaluated the effectiveness of these devices in the management of severe diabetic foot ulcers.

METHOD

This study (KereFish) is part of a multi-national, multi-centre, randomised, controlled clinical investigation (Odin) with patients suffering from deep diabetic wounds, allowing peripheral artery disease as evaluated by an ankle brachial index equal or higher than 0.6. The study has parallel treatment groups: Group 1 treatment with Kerecis® Omega3 Wound™ versus Group 2 treatment with standard of care. The primary objective is to test the hypothesis that a larger number of severe diabetic ulcers and amputation wounds, including those with moderate arterial disease, will heal in 16 weeks when treated with Kerecis® Omega3 Wound™ than with standard of care.

CONCLUSION

This study has received the ethics committee approval of each participating country. Inclusion of participants began in March 2020 and ended in July 2022. The first results will be presented in March 2023. The study is registered in ClinicalTrials.gov as Identifier: NCT04537520.

Spatially Guided Construction of Multilayered Epidermal Models Recapturing Structural Hierarchy and Cell-Cell Junctions

A current challenge in three-dimensional (3D) bioprinting of skin equivalents is to recreate the distinct basal and suprabasal layers and to promote their direct interactions. Such a structural arrangement is essential to establish 3D stratified epidermis disease models, such as for the autoimmune skin disease pemphigus vulgaris (PV), which targets the cell-cell junctions at the interface of the basal and suprabasal layers. Inspired by epithelial regeneration in wound healing, we develop a method that combines 3D bioprinting and spatially guided self-reorganization of keratinocytes to recapture the fine structural hierarchy that lies in the deep layers of the epidermis. Here, keratinocyte-laden fibrin hydrogels are bioprinted to create geographical cues, guiding dynamic self-reorganization of cells through collective migration, keratinocyte differentiation and vertical expansion. This process results in a region of self-organized multilayers (SOMs) that contain the basal to suprabasal transition, marked by the expressed levels of different types of keratins that indicate differentiation. Finally, we demonstrate the reconstructed skin tissue as an in vitro platform to study the pathogenic effects of PV and observe a significant difference in cell-cell junction dissociation from PV antibodies in different epidermis layers, indicating their applications in the preclinical test of possible therapies.

Platelet-rich plasma: a comparative and economical therapy for wound healing and tissue regeneration

Rise in the incidences of chronic degenerative diseases with aging makes wound care a socio-economic burden and unceasingly necessitates a novel, economical, and efficient wound healing treatment. Platelets have a crucial role in hemostasis and thrombosis by modulating distinct mechanistic phases of wound healing, such as promoting and stabilizing the clot. Platelet-rich plasma (PRP) contains a high concentration of platelets than naïve plasma and has an autologous origin with no immunogenic adverse reactions. As a consequence, PRP has gained significant attention as a therapeutic to augment the healing process. Since the past few decades, a robust volume of research and clinical trials have been performed to exploit extensive role of PRP in wound healing/tissue regeneration. Despite these rigorous studies and their application in diversified medical fields, efficacy of PRP-based therapies is continuously questioned owing to the paucity of large samplesizes, controlled clinical trials, and standard protocols. This review systematically delineates the process of wound healing and involvement of platelets in tissue repair mechanisms. Additionally, emphasis is laid on PRP, its preparation methods, handling, classification,application in wound healing, and PRP as regenerative therapeutics combined with biomaterials and mesenchymal stem cells (MSCs).

Bioengineering the Vascularized Endocrine Pancreas: A Fine-Tuned Interplay Between Vascularization, Extracellular-Matrix-Based Scaffold Architecture, and Insulin-Producing Cells

Intrahepatic islet transplantation is a promising β-cell replacement strategy for the treatment of type 1 diabetes. Instant blood-mediated inflammatory reactions, acute inflammatory storm, and graft revascularization delay limit islet engraftment in the peri-transplant phase, hampering the success rate of the procedure. Growing evidence has demonstrated that islet engraftment efficiency may take advantage of several bioengineering approaches aimed to recreate both vascular and endocrine compartments either ex vivo or in vivo. To this end, endocrine pancreas bioengineering is an emerging field in β-cell replacement, which might provide endocrine cells with all the building blocks (vascularization, ECM composition, or micro/macro-architecture) useful for their successful engraftment and function in vivo. Studies on reshaping either the endocrine cellular composition or the islet microenvironment have been largely performed, focusing on a single building block element, without, however, grasping that their synergistic effect is indispensable for correct endocrine function. Herein, the review focuses on the minimum building blocks that an ideal vascularized endocrine scaffold should have to resemble the endocrine niche architecture, composition, and function to foster functional connections between the vascular and endocrine compartments. Additionally, this review highlights the possibility of designing bioengineered scaffolds integrating alternative endocrine sources to overcome donor organ shortages and the possibility of combining novel immune-preserving strategies for long-term graft function.

The Role of the Extracellular Matrix (ECM) in Wound Healing: A Review

The extracellular matrix (ECM) is a 3-dimensional structure and an essential component in all human tissues. It is comprised of varying proteins, including collagens, elastin, and smaller quantities of structural proteins. Studies have demonstrated the ECM aids in cellular adherence, tissue anchoring, cellular signaling, and recruitment of cells. During times of integumentary injury or damage, either acute or chronic, the ECM is damaged. Through a series of overlapping events called the wound healing phases—hemostasis, inflammation, proliferation, and remodeling—the ECM is synthesized and ideally returned to its native state. This article synthesizes current and historical literature to demonstrate the involvement of the ECM in the varying phases of the wound healing cascade.

The effect of platelet-rich fibrin on wound healing following strabismus surgery

PURPOSE

To investigate the effect of platelet-rich fibrin (PRF) on post-operative wound healing following strabismus surgery in a rabbit model.

METHODS

Nine New Zealand white rabbits were involved in the study. One of these nine rabbits was kept in control without having any operation. Both eyes of eight rabbits underwent superior rectus muscle (SRM) resection. After resection of SRM, PRF was applied to SRM of the right eyes. In the left eye, SRM was not wrapped with PRF and served as a control. The rabbits were sacrificed and enucleated 6 weeks after the surgery. Inflammation and vascular proliferation were assessed by staining with haematoxylin-eosin. Scar and fibrosis were examined by the Masson trichrome staining. Immunohistochemical staining was performed for a vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (α-SMA).

RESULTS

There was no significant difference in terms of inflammation (p = 0.535), vascularization (p = 0.602), and fibrosis (p = 0.745) between the eyes. Immunohistochemical staining for VEGF demonstrated no significant difference (p = 0.745). However, significant staining for α-SMA was detected in PRF-treated eyes compared with control eyes (p = 0.037).

CONCLUSION

Consistent with the hypothesis that PRF facilitates wound healing as a biocatalyst, there was only a significant difference for α-SMA related to myofibroblast activity which is important for wound remodelling. Future comprehensive studies are needed to extend these results.

Clinical Evaluation of the Efficacy and Tolerability of Rigenase® and Polyhexanide (Fitostimoline® Plus) vs. Hyaluronic Acid and Silver Sulfadiazine (Connettivina® Bio Plus) for the Treatment of Acute Skin Wounds: A Randomized Trial

OBJECTIVES

Compare the efficacy and tolerability of Connettivina® Bio Plus (Group A) gauze and cream, and Fitostimoline® Plus (Group B) gauze and cream for the treatment of acute superficial skin lesions.

DESIGN

Single-center, parallel, randomized trial. A block randomization method was used.

SETTING

University of Salerno-AOU San Giovanni di Dio e Ruggi d'Aragona.

PARTICIPANTS

Sixty patients were enrolled. All patients fulfilled the study requirements.

INTERVENTION

One application of the study drugs every 24 h, and a six-week observation period.

MAIN OUTCOME MEASURES

Efficacy and tolerability of the study drugs.

RESULTS

In total, 60 patients (Group A, n = 30; Group B, n = 30) were randomized; mean age was 58.5 ± 15.8 years. All patients were included in the outcome analysis. Total wound healing was achieved in 17 patients undergoing treatment with Connettivina® Bio Plus and 28 patients undergoing treatment with Fitostimoline® Plus. The greater effectiveness of the latter was significant (p = 0.00104). In Group B, a significantly greater degree of effectiveness was observed in reducing the fibrin in the wound bed (p = 0.04746). Complications or unexpected events were not observed.

CONCLUSIONS

Both Connettivina® Bio Plus and Fitostimoline® Plus are secure and effective for treating acute superficial skin lesions. Fitostimoline® Plus was more effective than Connettivina® Bio Plus in wound healing of acute superficial skin lesions, especially if fibrin had been observed in the wound bed.

Droplet-based bioprinting enables the fabrication of cell–hydrogel–microfibre composite tissue precursors

Composites offer the option of coupling the individual benefits of their constituents to achieve unique material properties, which can be of extra value in many tissue engineering applications. Strategies combining hydrogels with fibre-based scaffolds can create tissue constructs with enhanced biological and structural functionality. However, developing efficient and scalable approaches to manufacture such composites is challenging. Here, we use a droplet-based bioprinting system called reactive jet impingement (ReJI) to integrate a cell-laden hydrogel with a microfibrous mesh. This system uses microvalves connected to different bioink reservoirs and directed to continuously jet bioink droplets at one another in mid-air, where the droplets react and form a hydrogel that lands on a microfibrous mesh. Cell–hydrogel–fibre composites are produced by embedding human dermal fibroblasts at two different concentrations (5 × 106 and 30 × 106 cells/mL) in a collagen–alginate–fibrin hydrogel matrix and bioprinted onto a fibre-based substrate. Our results show that both types of cell–hydrogel–microfibre composite maintain high cell viability and promote cell–cell and cell–biomaterial interactions. The lower fibroblast density triggers cell proliferation, whereas the higher fibroblast density facilitates faster cellular organisation and infiltration into the microfibres. Additionally, the fibrous component of the composite is characterised by high swelling properties and the quick release of calcium ions. The data indicate that the created composite constructs offer an efficient way to create highly functional tissue precursors for laminar tissue engineering, particularly for wound healing and skin tissue engineering applications.

Graphic abstract

Treatment of oroantral communication with Platelet-Rich Fibrin: A systematic review

BACKGROUND

Oroantral communication (OAC) is the opening between the maxillary sinus and the oral cavity, which constitutes a gate for the mucosal infection in the maxillary sinus. On the other hand, an OAF develops when the OAC does not close spontaneously, remains manifest and is epithelialized. Several methods have been proposed to solve these situations, however, they are associated with increased postoperative morbidity and/or higher associated costs and require some experience of the surgeon to perform them. To overcome these disadvantages, the use of Platelet-Rich Fibrin (PRF) is proposed. The present study aims to perform a systematic review of the literature, collecting cases in which PRF was used in the treatment of OACs/OAFs.

MATERIALS AND METHODS

An electronic search of the MEDLINE database (via PubMed) and Web of Science was performed using the following MeSH terms (Medical Subjects Headings): (oroantral communication OR oroantral fistula OR buccosinusal communication) AND (platelet-rich fibrin OR prf OR fibrin mesh). The criteria used were those described by the PRISMA® Statement. The search was not time-restricted and was updated to April 2021.

RESULTS

After searching, 11 articles were included that met the established criteria. In these, PRF was used alone or in combination with bi- or trilaminar techniques achieving complete resolution in 100% of cases (n = 116).

CONCLUSIONS

With the limitations of this study, it can be established that PRF can be used alone for the treatment of OACs/OAFs up to 5 mm and, in larger defects, it is advisable to combine it with bi- or trilaminar techniques. PRF is an effective therapeutic option, with minimal associated postoperative morbidity compared to other techniques and allows the position of the mucogingival junction to be preserved. Its combination with bone grafting improves the starting point before the replacement of the missing tooth with a dental implant.

Inflammatory Microenvironment of Skin Wounds

Wound healing is a dynamic and highly regulated process that can be separated into three overlapping and interdependent phases: inflammation, proliferation, and remodelling. This review focuses on the inflammation stage, as it is the key stage of wound healing and plays a vital role in the local immune response and determines the progression of wound healing. Inflammatory cells, the main effector cells of the inflammatory response, have been widely studied, but little attention has been paid to the immunomodulatory effects of wound healing in non-inflammatory cells and the extracellular matrix. In this review, we attempt to deepen our understanding of the wound-healing microenvironment in the inflammatory stage by focusing on the interactions between cells and the extracellular matrix, as well as their role in regulating the immune response during the inflammatory stage. We hope our findings will provide new ideas for promoting tissue regeneration through immune regulation.

Contracting scars from fibrin drops

This paper describes a microscale fibroplasia and contraction model that is based on fibrin-embedded lung fibroblasts and provides a convenient visual readout of fibrosis. Cell-laden fibrin microgel drops are formed by aqueous two-phase microprinting. The cells deposit extracellular matrix (ECM) molecules such as collagen while fibrin is gradually degraded. Ultimately, the cells contract the collagen-rich matrix to form a compact cell-ECM spheroid. The size of the spheroid provides the visual readout of the extent of fibroplasia. Stimulation of this wound-healing model with the profibrotic cytokine TGF-β1 leads to an excessive scar formation response that manifests as increased collagen production and larger cell-ECM spheroids. Addition of drugs also shifted the scarring profile: the FDA-approved fibrosis drugs (nintedanib and pirfenidone) and a PAI-1 inhibitor (TM5275) significantly reduced cell-ECM spheroid size. Not only is the assay useful for evaluation of antifibrotic drug effects, it is relatively sensitive; one of the few in vitro fibroplasia assays that can detect pirfenidone effects at submillimolar concentrations. Although this paper focuses on lung fibrosis, the approach opens opportunities for studying a broad range of fibrotic diseases and for evaluating antifibrotic therapeutics.

Immunomodulation of Skin Repair: Cell-Based Therapeutic Strategies for Skin Replacement (A Comprehensive Review)

The immune system has a crucial role in skin wound healing and the application of specific cell-laden immunomodulating biomaterials emerged as a possible treatment option to drive skin tissue regeneration. Cell-laden tissue-engineered skin substitutes have the ability to activate immune pathways, even in the absence of other immune-stimulating signals. In particular, mesenchymal stem cells with their immunomodulatory properties can create a specific immune microenvironment to reduce inflammation, scarring, and support skin regeneration. This review presents an overview of current wound care techniques including skin tissue engineering and biomaterials as a novel and promising approach. We highlight the plasticity and different roles of immune cells, in particular macrophages during various stages of skin wound healing. These aspects are pivotal to promote the regeneration of nonhealing wounds such as ulcers in diabetic patients. We believe that a better understanding of the intrinsic immunomodulatory features of stem cells in implantable skin substitutes will lead to new translational opportunities. This, in turn, will improve skin tissue engineering and regenerative medicine applications.

Immuno-histopathologic evaluation of mineralized plasmatic matrix in the management of horizontal ridge defects in a canine model (a split-mouth comparative study)

Our research aimed to investigate the effect of combining biphasic calcium phosphate (BCP) alloplast with mineralized plasmatic matrix (MPM) as compared with platelet-rich fibrin (PRF) on the quality and quantity of bone formation and maturation at surgically created horizontal critical-sized ridge defects (HRDs) in a canine model. We used a split-mouth design using the third and fourth mandibular premolars of the mongrel dogs. Twelve defects on the left side (experimental group, I) were managed with MPM composite mixed with BCP alloplast, MPM compact layer. On the right side (control group, II), another 12 defects were managed with PRF mixed with BCP alloplast, followed by the application of PRF compact strips. Finally, both were covered by a collagen membrane. Dogs were euthanized at 4, 8, and 12 weeks, and the studied defects were processed to evaluate treatment outcome, including mean percentage of bone surface area, collagen percentage, and osteopontin (OPN) immunoreaction. Our results revealed that the mean percentage of bone surface area was significantly increased in the experimental group treated with MPM at all time intervals as compared with the PRF group. Decreased collagen percentage and increased OPN immunoreactivity showed significant results in the MPM group as compared with PRF at 4 and 8 weeks postoperatively, respectively. In conclusion, MPM accelerates the formation of superior new bone quality when used in the treatment of HRDs.

Revisiting the potential of South American rattlesnake Crotalus durissus terrificus toxins as therapeutic, theranostic and/or biotechnological agents

The potential biotechnological and biomedical applications of the animal venom components are widely recognized. Indeed, many components have been used either as drugs or as templates/prototypes for the development of innovative pharmaceutical drugs, among which many are still used for the treatment of human diseases. A specific South American rattlesnake, named Crotalus durissus terrificus, shows a venom composition relatively simpler compared to any viper or other snake species belonging to the Crotalus genus, although presenting a set of toxins with high potential for the treatment of several still unmet human therapeutic needs, as reviewed in this work. In addition to the main toxin named crotoxin, which is under clinical trials studies for antitumoral therapy and which has also anti-inflammatory and immunosuppressive activities, other toxins from the C. d. terrificus venom are also being studied, aiming for a wide variety of therapeutic applications, including as antinociceptive, anti-inflammatory, antimicrobial, antifungal, antitumoral or antiparasitic agent, or as modulator of animal metabolism, fibrin sealant (fibrin glue), gene carrier or theranostic agent. Among these rattlesnake toxins, the most relevant, considering the potential clinical applications, are crotamine, crotalphine and gyroxin. In this narrative revision, we propose to organize and present briefly the updates in the accumulated knowledge on potential therapeutic applications of toxins collectively found exclusively in the venom of this specific South American rattlesnake, with the objective of contributing to increase the chances of success in the discovery of drugs based on toxins.

A mechanistic survey of Alzheimer's disease

Alzheimer's disease (AD) is the most common, age-dependent neurodegenerative disorder. While AD has been intensively studied from different aspects, there is no effective cure for AD, largely due to a lack of a clear mechanistic understanding of AD. In this mini-review, we mainly focus on the discussion and summary of mechanistic causes of Alzheimer's disease (AD). While different AD mechanisms illustrate different molecular and cellular pathways in AD pathogenesis, they do not necessarily exclude each other. Instead, some of them could work together to initiate, trigger, and promote the onset and development of AD. In a broader viewpoint, some AD mechanisms (e.g., amyloid aggregation mechanism, microbial infection/neuroinflammation mechanism, and amyloid cross-seeding mechanism) could also be applicable to other amyloid diseases including type II diabetes, Parkinson's disease, and prion disease. Such common mechanisms for AD and other amyloid diseases explain not only the pathogenesis of individual amyloid diseases, but also the spreading of pathologies between these diseases, which will inspire new strategies for therapeutic intervention and prevention for AD.

Harnessing Multifaceted Next-Generation Technologies for Improved Skin Wound Healing

Dysregulation of sequential and synchronized events of skin regeneration often results in the impairment of chronic wounds. Conventional wound dressings fail to trigger the normal healing mechanism owing to the pathophysiological conditions. Tissue engineering approaches that deal with the fabrication of dressings using various biomaterials, growth factors, and stem cells have shown accelerated healing outcomes. However, most of these technologies are associated with difficulties in scalability and cost-effectiveness of the products. In this review, we survey the latest developments in wound healing strategies that have recently emerged through the multidisciplinary approaches of bioengineering, nanotechnology, 3D bioprinting, and similar cutting-edge technologies to overcome the limitations of conventional therapies. We also focus on the potential of wearable technology that supports complete monitoring of the changes occurring in the wound microenvironment. In addition, we review the role of advanced devices that can precisely enable the delivery of nanotherapeutics, oligonucleotides, and external stimuli in a controlled manner. These technological advancements offer the opportunity to actively influence the regeneration process to benefit the treatment regime further. Finally, the clinical relevance, trajectory, and prospects of this field have been discussed in brief that highlights their potential in providing a beneficial wound care solution at an affordable cost.

Efficacy of a new-generation platelet-rich fibrin in the treatment of periodontal intrabony defects: a randomized clinical trial

Background

The aim of the study was to clinically evaluate the healing of intrabony defects after treatment with a new generation of platelet-rich fibrin (A-PRF+) respect to enamel matrix derivative (EMD).

Methods

Thirty (30) intrabony defects of 18 patients (9 males, 9 females) were randomly treated with A-PRF+ (test, n = 15) or EMD (control, n = 15). The following clinical parameters were recorded at baseline and 6 months after surgery: pocket depth (PD), gingival recession (GR) and clinical attachment level (CAL). After debridement the intrabony defects were filled with A-PRF+ in the test group, respectively with EMD in the control group, and fixed with sutures to ensure wound closure and stability.

Results

Both treatment methods resulted in statistically significant PD reductions, respectively CAL gains six months post-operatively. No statistically significant differences were found between the two groups as the mean CAL gain was 2.33 ± 1.58 mm in the A-PRF+ group, respectively 2.60 ± 1.18 mm in the EMD group (p < 0.001).

Conclusion

Within the limits of this study the new-generation platelet-rich fibrin seems to be as clinically effective as EMD during surgical treatment of intrabony defects. Treatment with A-PRF+ or EMD resulted in reliable clinical outcomes. The use of A-PRF+ as a human autologous product can give a positive impact on periodontal healing.

Clinical Relevance A-PRF+ may be suitable for the treatment of intrabony periodontal defects.

Trial registration number (TRN) NCT04404374 (ClinicalTrials.gov ID).

H2S signaling and extracellular matrix remodeling in cardiovascular diseases: A tale of tense relationship

Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network that not only provides mechanical support but also transduces essential molecular signals in organ functions. ECM is constantly remodeled to control tissue homeostasis, responsible for cell adhesion, cell migration, cell-to-cell communication, and cell differentiation, etc. The dysregulation of ECM components contributes to various diseases, including cardiovascular diseases, fibrosis, cancer, and neurodegenerative diseases, etc. Aberrant ECM remodeling is initiated by various stress, such as oxidative stress, inflammation, ischemia, and mechanical stress, etc. Hydrogen sulfide (H₂S) is a gasotransmitter that exhibits a wide variety of cytoprotective and physiological functions through its anti-oxidative and anti-inflammatory actions. Amounting research shows that H₂S can attenuate aberrant ECM remodeling. In this review, we discussed the implications and mechanisms of H₂S in the regulation of ECM remodeling in cardiovascular diseases, and highlighted the potential of H₂S in the prevention and treatment of cardiovascular diseases through attenuating adverse ECM remodeling.

Sutureless "Contact Lens Sandwich" Technique for Amniotic Membrane Therapy of Central Corneal Ulcers

PURPOSE

To describe a new technique for sutureless and glue-free amniotic membrane transplantation (AMT) and to investigate its effectiveness to treat corneal persistent epithelial defects (PEDs), compared to bandage contact lens (BCL) application alone.

METHODS

We performed AMT with "contact lens sandwich technique" (CLS-AMT) in 8 consecutive patients with central/para-central (up to 4.00 mm from the geometrical centre) PED/ulceration and we retrospectively compared the results with 11 BCL procedures.

RESULTS

The procedures were performed successfully with no complications.CLS-AMT showed significantly shorter healing time than BCL (24.0  ±  19.1 vs 42.9  ±  14.6 days; P < 0.05, Mann-Whitney test). Recurrence rates were 12% and 27% for CLS-AMT and BCL, respectively.

CONCLUSION

CLS-AMT technique, based on the suction effect due to the superposition of a bandage contact lens on the AM-ring complex, represents a quick, low cost, easy to perform and nearly non-invasive AMT technique. This approach is able to provide adequate fixation of AM, and it seems to be a safe and effective treatment for patients with PEDs.

Application of platelet-rich fibrin grafts following pterygium excision

PURPOSE

To compare the efficacy, safety and recurrence rate of platelet-rich fibrin (PRF) grafts and limbal conjunctival autografts (LCAs) following pterygium excision.

METHODS

A total of 108 patients (108 eyes) with primary pterygium were included in this study and were divided into group A (56 eyes) and group B (52 eyes). Patients in group A underwent excision of the pterygium followed by LCA while patients in group B underwent PRF grafts following pterygium excision. The PRF was produced using the patient's own whole-blood sample by centrifugation and extrusion. The surgery time, intraoperative complications, postoperative complications, recurrence rate, intraocular pressure (IOP) and follow-up period were recorded and evaluated between the two groups.

RESULTS

The mean surgery time was significantly shorter in group B (25.0 ± 4.2 min) than in group A (36.5 ± 6.3 min) (P < .001). Recurrence was observed in two cases (3.6%) in group A while no recurrence was observed in group B. No graft loss was observed in either group. No other intra/postoperative complications such as a tear in the graft, injury to the medial rectus muscle, excessive bleeding, scleral necrosis, graft oedema, graft necrosis, pannus formation or symblepharon appeared in either group.

CONCLUSIONS

This study presented with a promising outcome of PRF graft applications in primary pterygium surgery. The use of PRF following pterygium excision is a simple, easily applicable, and comfortable method for both patients and surgeons, with less time consumption, recurrence rate and complications, which could be widely used in pterygium management.