Role of autologous rabbit adipose-derived stem cells in the early phases of the repairing process of critical bone defects

Safety of a Porous Hydroxyapatite Bone Substitute in Orthopedics and Traumatology: A Multi-Centric Clinical Study

The development of biomaterials in recent years has made it possible to broaden their use in the surgical field. Although iliac crest bone graft harvesting currently remains the gold standard as an autograft, the properties of hydroxyapatite bone substitutes appear to be beneficial. The first fundamental step to consider is the safety of using these devices. The purpose of this retrospective cohort study is to consider all the adverse events observed in our population and assess their relationships with the bone substitute device. The population analyzed consisted of patients undergoing trauma osteosynthesis with at least one implanted porous hydroxyapatite device. We considered a court of 114 patients treated at "Azienda Ospedaliera Universitaria di Ferrara-U.O. di Ortopedia e Traumatologia" in the period from January 2015 to December 2022. Upon analyzing our population, no adverse events related to the device emerged. Taking into consideration different study groups from other National Hospital Centers, no critical issues were detected except for three cases of extrusion of the biomaterial. It is necessary to clarify that bone substitutes cannot replace compliance with the correct principles linked to the biomechanics of osteosynthesis. This report outlines a safety profile for the use of these devices as bone substitutes in trauma orthopedic surgery.

Autologous adipose-derived mesenchymal stem cells and hydroxyapatite for bone defect in rabbits

This study aims to evaluate the effect of autologous adipose-derived mesenchymal stem cells (AAD-MSC), with and without synthetic absorbable hydroxyapatite (HAP-91), on the bone regeneration in rabbits. Thirty-four female white New Zealand rabbits were submitted to a 10 mm distal diaphyseal radius ostectomy, divided into 3 experimental groups according to the treatment established. The bone gap was filled with 0.15 ml of a 0.9% saline solution containing two million AAD-MSC (G1), or AAD-MSC associated with HAP-91 (G2). The control group (CG) received only 0.15 ml of the 0.9% saline solution. Radiographs were made post-operatively, and after 15, 30, 45 and 90 days. Fifty percent of the samples were submitted to a histological examination at 45 days and the remaining ones at 90 days post-operatively. Radiographically, the periosteal reaction, bone callus volume and bone bridge quality were superior in G2 (P < 0.05). Histologically, the bone repair was faster and more efficient in G1 at 45 days (P < 0.05). In conclusion, AAD-MSC improved the regeneration on the experimentally induced bone defects in rabbits; however, the use of hydroxyapatite requires caution given the granulomatous reaction produced in the species.

Current evidence on potential of adipose derived stem cells to enhance bone regeneration and future projection

Injuries to the postnatal skeleton are naturally repaired through successive steps involving specific cell types in a process collectively termed “bone regeneration”. Although complex, bone regeneration occurs through a series of well-orchestrated stages wherein endogenous bone stem cells play a central role. In most situations, bone regeneration is successful; however, there are instances when it fails and creates non-healing injuries or fracture nonunion requiring surgical or therapeutic interventions. Transplantation of adult or mesenchymal stem cells (MSCs) defined by the International Society for Cell and Gene Therapy (ISCT) as CD105+CD90+CD73+CD45-CD34-CD14orCD11b-CD79αorCD19-HLA-DR- is being investigated as an attractive therapy for bone regeneration throughout the world. MSCs isolated from adipose tissue, adipose-derived stem cells (ADSCs), are gaining increasing attention since this is the most abundant source of adult stem cells and the isolation process for ADSCs is straightforward. Currently, there is not a single Food and Drug Administration (FDA) approved ADSCs product for bone regeneration. Although the safety of ADSCs is established from their usage in numerous clinical trials, the bone-forming potential of ADSCs and MSCs, in general, is highly controversial. Growing evidence suggests that the ISCT defined phenotype may not represent bona fide osteoprogenitors. Transplantation of both ADSCs and the CD105^- sub-population of ADSCs has been reported to induce bone regeneration. Most notably, cells expressing other markers such as CD146, AlphaV, CD200, PDPN, CD164, CXCR4, and PDGFRα have been shown to represent osteogenic sub-population within ADSCs. Amongst other strategies to improve the bone-forming ability of ADSCs, modulation of VEGF, TGF-β1 and BMP signaling pathways of ADSCs has shown promising results. The U.S. FDA reveals that 73% of Investigational New Drug applications for stem cell-based products rely on CD105 expression as the “positive” marker for adult stem cells. A concerted effort involving the scientific community, clinicians, industries, and regulatory bodies to redefine ADSCs using powerful selection markers and strategies to modulate signaling pathways of ADSCs will speed up the therapeutic use of ADSCs for bone regeneration.

Efficacy of adipose tissue-derived stem cells in locomotion recovery after spinal cord injury: a systematic review and meta-analysis on animal studies

BACKGROUND

Considerable disparities exist on the use of adipose tissue-derived stem cells (ADSCs) for treatment of spinal cord injury (SCI). Hence, the current systematic review aimed to investigate the efficacy of ADSCs in locomotion recovery following SCI in animal models.

METHODS

A search was conducted in electronic databases of MEDLINE, Embase, Scopus, and Web of Science until the end of July 2019. Reference and citation tracking and searching Google and Google Scholar search engines were performed to achieve more studies. Animal studies conducted on rats having SCI which were treated with ADSCs were included in the study. Exclusion criteria were lacking a non-treated control group, not evaluating locomotion, non-rat studies, not reporting the number of transplanted cells, not reporting isolation and preparation methods of stem cells, review articles, combination therapy, use of genetically modified ADSCs, use of induced pluripotent ADSCs, and human trials. Risk of bias was assessed using Hasannejad et al.'s proposed method for quality control of SCI-animal studies. Data were analyzed in STATA 14.0 software, and based on a random effect model, pooled standardized mean difference with a 95% confidence interval was presented.

RESULTS

Of 588 non-duplicated papers, data from 18 articles were included. Overall risk of bias was high risk in 8 studies, some concern in 9 studies and low risk in 1 study. Current evidence demonstrated that ADSCs transplantation could improve locomotion following SCI (standardized mean difference = 1.71; 95%CI 1.29-2.13; p < 0.0001). A considerable heterogeneity was observed between the studies (I² = 72.0%; p < 0.0001). Subgroup analysis and meta-regression revealed that most of the factors like injury model, the severity of SCI, treatment phase, injury location, and number of transplanted cells did not have a significant effect on the efficacy of ADSCs in improving locomotion following SCI (p_{for odds ratios} > 0.05).

CONCLUSION

We conclude that any number of ADSCs by any prescription routes can improve locomotion recovery in an SCI animal model, at any phase of SCI, with any severity. Given the remarkable bias about blinding, clinical translation of the present results is tough, because in addition to the complexity of the nervous system and the involvement of far more complex motor circuits in the human, blinding compliance and motor outcome assessment tests in animal studies and clinical trials are significantly different.

Mandibular bone regeneration with autologous adipose-derived mesenchymal stem cells and coralline hydroxyapatite: experimental study in rats

The purpose of this paper was to investigate the bone regeneration effect of autologous adipose tissue mesenchymal stem cells (ATMSC) in a small animal model. Twelve Wistar rats were given bilateral critical-size defects in the mandible. The defects were filled with coralline hydroxyapatite alone or combined with autologous undifferentiated ATMSC obtained from the dorsal fat pad. Studies were conducted at three and six weeks. Descriptive histology and histomorphometry revealed a significant (p < 0.05) increased bone regeneration values in the cell-treated defects at both three and six weeks. ATMSC promoted the formation of new bone in the central areas of the defects and in the scaffold micropores, both in a higher state of maturation. Autologous undifferentiated ATMSC enhanced bony healing of mandibular critical-size defects in rats when implanted with a coralline hydroxyapatite scaffold.

Local administration of allogeneic or autologous bone marrow-derived mesenchymal stromal cells enhances bone formation similarly in distraction osteogenesis

BACKGROUND AIMS

Distraction osteogenesis (DO) is a surgical technique to promote bone regeneration that requires a long time for bone healing. Bone marrow-derived mesenchymal stromal cells (MSCs) have been applied to accelerate bone formation in DO. Allogeneic MSCs are attractive, as they could be ready to use in clinics. Whether allogeneic MSCs would have an effect similar to autologous MSCs with regard to promoting bone formation in DO is still unknown. This study compares the effect of autologous MSCs versus allogeneic MSCs on bone formation in a rat DO model.

METHODS

Rat bone marrow-derived MSCs were isolated, characterized and expanded in vitro. Adult rats were subjected to right tibia transverse osteotomy. On the third day of distraction, each rat received one injection of phosphate-buffered saline (PBS), autologous MSCs or allogeneic MSCs at the distraction site. Tibiae were harvested after 28 days of consolidation for micro-computed tomography examination, mechanical test and histological analysis.

RESULTS

Results showed that treatment with both allogeneic and autologous MSCs promoted bone formation, with significantly higher bone mass, mechanical properties and mineral apposition rate as well as expression of angiogenic and bone formation markers at the regeneration sites compared with the PBS-treated group. No statistical difference in bone formation was found between the allogeneic and autologous MSC treatment groups.

CONCLUSIONS

This study indicates that allogeneic and autologous MSCs have a similar effect on promoting bone consolidation in DO. MSCs from an allogeneic source could be used off-the-shelf with DO to achieve early bone healing.

Bone regeneration with autologous adipose-derived mesenchymal stem cells: A reliable experimental model in rats

The adult mesenchymal stem cell (MSC) has been proposed to be the definitive tool in regenerative medicine due to its multi-differentiation potential and expansion capacity ex vivo. The use of MSCs on bone regeneration has been assessed in several studies, obtaining promising results. However, the endless combinations that can be tested and the heterogeneity in the experimental conditions become a drawback when comparing results between authors. Moreover, it is very hard to find autologous studies using adipose-derived MSCs (AD-MSC) in rodents, which is the most used preclinical animal model.

In this article an experimental model for basic bone tissue engineering research is described and justified, on which adult AD-MSCs are safely isolated from the rat dorsal interscapular fat pad, allowing ex vivo expansion and autogenous orthotopic reimplantation in a bilateral mandibular bone defect made in the same animal.

This reliable and reproducible model provides a simple way to perform basic experimentation studies in a small animal model using autologous MSC for bone regeneration or cell therapy techniques prior to improve the research on large animal models.•

Predictable and safe harvest of adipose-derived MSC. No need of animal sacrifice.

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Allows for autologous studies with the most frequently used animal model: the rat. No need of allogeneic or human MSC use and, therefore, immunological concerns are avoided.

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Bilateral mandibular critical size defect to allow direct control/experimental comparison.

Rat bone healing induced by natural nanocrystalline carbonated hydroxyapatite in combination with human amniotic fluid stem cells (AFSCs)

The present study was aimed at identifying a new scaffold/stem cell combination useful to treat large bone defects. Human amniotic fluid stem cells (AFSCs) were expanded in vitro, labeled with a fluorescent cell-permeable dye (PKH26) and transplanted in vivo in a femoral injured rat model. The femoral defect was left untreated (control rats) or filled with hydroxyapatite (HA; natural nanocrystalline carbonated hydroxyapatite-Orthoss®) scaffold alone or loaded with PKH26-labeled AFSCs. All animals were killed 3 weeks after implantation. Both gross anatomy and histological observations revealed a major bone regenerative response in rat specimens treated with HA scaffold, alone or supplemented with AFSCs. Samples injected with HA plus AFSCs displayed the presence of abundant fibrotic tissue, the formation of periosteal woven bone, and an increased presence of blood vessels in the bone marrow, with still fluorescent AFSCs in close proximity. These observations provide evidence that natural HA plus AFSCs represents a promising alternative therapeutic strategy to autologous bone grafting procedures.

Gingival mesenchymal stem cells as an alternative source to bone marrow mesenchymal stem cells in regeneration of bone defects: In vivo study

Healing of critical sized bone defects represents a challenging issue in clinical and research fields. Current therapeutic techniques, such as bone grafts or bone grafts substitutes, still have limitations and drawbacks. Therefore, stem cell-based therapy provides a prospective approach to enhance bone regeneration. The present study aimed to assess the regenerative capacity of Gingival mesenchymal stem cells (GMSCs) as well as Bone marrow mesenchymal stem cells (BMSCs) loaded on NanoBone scaffold, in comparison to the unloaded one, in surgically created bone defects in rabbits' tibiae. To achieve this aim, critical sized bone defects, of 6-mm diameter each, were unilaterally created in tibiae of adult New Zeeland male white rabbits (n = 27). The rabbits were then divided randomly into three groups (9 each) and received the following: Group I: Unloaded NanoBone Scaffold, Group II: GMSCs Loaded on NanoBone Scaffold, and Group III: BMSCs Loaded on NanoBone Scaffold. Three rabbits from each group were then sacrificed at each time point (2, 4 and 6 weeks postoperatively), tibiae were dissected out to evaluate bone healing in the created bony defects; both histologically and histomorphometrically. The findings of this study indicate that both GMSCs and BMSCs exhibited fibroblast morphology and expressed phenotypic MSCs markers. Histologically, local application of GMSCs and BMSCs loaded on NanoBone scaffold showed enhanced the pattern of bone regeneration as compared to the unloaded scaffold. Histomorphometrically, there was astatistically insignificant difference in the new bone area % between the bony defects treated with GMSCs and BMSCs. Thus, GMSCs can be considered as a comparable alternative source to BMSCs in bone regeneration.

Calvarial Versus Long Bone: Implications for Tailoring Skeletal Tissue Engineering

Tissue-engineered graft substitutes have shown great potential to treat large bone defects. While we usually assume that therapeutic approaches developed for appendicular bone healing could be similarly translated for application in craniofacial reconstruction and vice versa, this is not necessarily accurate. In addition to those more well-known healing-associated factors, such as age, lifestyle (e.g., nutrition and smoking), preexisting disease (e.g., diabetes), medication, and poor blood supply, the developmental origins and surrounding tissue of the wound sites can largely affect the fracture healing outcome as well as designed treatments. Therefore, the strategies developed for long bone fracture repair might not be suitable or directly applicable to skull bone repair. In this review, we discuss aspects of development, healing process, structure, and tissue engineering considerations between calvarial and long bones to assist in designing the tailored bone repair strategies. Impact Statement We summarized, in this review, the existing body of knowledge between long bone and calvarial bone with regard to their development and healing, tissue structure, and consideration of current tissue engineering strategies. By highlighting their similarities and differences, we propose that tailored tissue engineering strategies, such as scaffold features, growth factor usage, and the source of cells for tissue or region-specific bone repair, are necessary to ensure an optimized healing outcome.

Adipose-derived stem cell sheets accelerate bone healing in rat femoral defects

In the present study, we investigated whether both adipose-derived stem cell (ADSC) and osteogenic-induced ADSC sheets could promote bone healing in a rat distal femoral metaphysis bone defect model. A through-hole defect of 1 mm diameter was drilled into each distal femur of 12 week old rats. Forty-five rats were randomly assigned to three groups: (1) control group; (2) ADSC sheet group; or (3) osteogenic-induced ADSC sheet group. We evaluated each group by analysis of computerized tomography scans every week after the surgery, histological analysis, and DiI labeling (a method of membrane staining for post implant cell tracing). Radiological and histological evaluations showed that a part of the hole persisted in the control group at four weeks after surgery, whereas the hole was restored almost completely by new bone formation in both sheet groups. The mean value of bone density (in Houndsfield units) for the bone defect area was significantly higher in both sheet groups than that in the control group (p = 0.05) at four weeks postoperative. A large number of osteocalcin positive osteoblasts were observed at the area of bone defect, especially in the osteogenic-induced ADCS sheet group. DiI labeling in the newly formed bone showed that each sheet had differentiated into bone tissue at four weeks after surgery. The ADSC and the osteogenic-induced ADSC sheets promoted significantly quicker bone healing in the bone defect. Moreover, the osteogenic-induced ADSC sheet may be more advantageous for bone healing than the ADSC sheet because of the higher number of osteocalcin positive osteoblasts via the transplantation.

Autologous Mesenchymal Stroma Cells Are Superior to Allogeneic Ones in Bone Defect Regeneration

The application of autologous mesenchymal stem cells (MSC) for the treatment of bone defects requires two invasive procedures and several weeks of ex vivo cell expansion. To overcome these limitations, the administration of allogeneic MSC may be attractive, because they are anticipated to be immunoprivileged. Because preclinical studies using various animal models are conflicting with respect to the efficacy of allogeneic MSC, we investigated whether autologous and allogeneic human MSC (hMSC) are equally effective in regenerating bone in a humanized mouse model resembling the human immune system. Applying autologous and allogeneic hMSC in critically sized femoral defects, we found that allogeneic hMSC elicited a mild immune response early after implantation, whereas early angiogenic processes were similar in both treatments. At later healing time points, the transplantation of allogeneic hMSC resulted in less bone formation than autologous hMSC, associated with a reduced expression of the osteogenic factor Runx2 and impaired angiogenesis. We found by species-specific staining for collagen-type-1α2 that MSCs of either source did not synthesize new bone matrix, indicating an indirect contribution of transplanted hMSC to bone regeneration. In conclusion, our data suggest that the application of autologous hMSC is superior to that of allogeneic cells for bone defect treatment.

Microencapsulated rabbit adipose stem cells initiate tissue regeneration in a rabbit ear defect model

Cell-based tissue engineering can promote cartilage tissue regeneration, but cell retention in the implant site post-delivery is problematic. Alginate microbeads containing adipose stem cells (ASCs) pretreated with chondrogenic media have been used successfully to regenerate hyaline cartilage in critical size defects in rat xiphoid suggesting that they may be used to treat defects in elastic cartilages such as the ear. To test this, we used microbeads made with low viscosity, high mannuronate medical grade alginate using a high electrostatic potential, and a calcium cross linking solution containing glucose. Microbeads containing rabbit ASCs (rbASCs) were implanted bilaterally in 3 mm critical size midcartilage ear defects of six skeletally mature male New Zealand White rabbits (empty defect; microbeads without cells; microbeads with cells; degradable microbeads with cells; and autograft). Twelve weeks post-implantation, regeneration was assessed by microCT and histology. Microencapsulated rbASCs cultured in chondrogenic media expressed mRNAs for aggrecan, Type II collagen, and Type X collagen. Histologically, empty defects contained fibrous tissue; microbeads without cells were still present in defects and were surrounded by fibrous tissue; nondegradable beads with rbASCs initiated cartilage regeneration; degradable microbeads with cells produced immature bone-like tissue, also demonstrated by microCT; and autografts appeared as normal auricular cartilage but were not fully integrated with the tissue surrounding the defect. Elastin, the hallmark of auricular cartilage, was not evident in the neocartilage. This delivery system offers the potential for regeneration of auricular cartilage, but vascularity of the treatment site and use of factors that induce elastin must be considered.

Histological Evaluation of Bone Repair with Hydroxyapatite: A Systematic Review

The aim of this study was to evaluate the morphological bone response in animal experiments by applying hydroxyapatite grafts in critical and non-critical size bone defects. Current report followed the guidelines established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Animal experiments were selected by assessing repair of bone defects with hydroxyapatite as bone graft and with blood clot only as control. Eight articles were identified in specialized literature and included in the meta-analysis. Statistical analysis was carried out with a random-effect model (p = 0.05). Subgroup analyses were further performed to investigate bone repair in critical and non-critical bone defects. Comprehensive analysis of bone repair outcome showed a statistically significant difference between hydroxyapatite and blood clot control (p < 0.05). Subgroup analyses showed statistically significant difference for critical bone defects (p < 0.05). No statistically significant difference was reported in non-critical bone defects (p > 0.05). Although animal studies revealed a high risk of bias and results should be interpreted with caution, the literature suggests that non-critical bone defects may heal spontaneously and without the need of a bone graft. Conversely, when critical-size defects are present, the use of hydroxyapatite bone graft improves the bone repair process.

Adipose-derived stromal cell in regenerative medicine: A review

The application of appropriate cell origin for utilizing in regenerative medicine is the major issue. Various kinds of stem cells have been used for the tissue engineering and regenerative medicine. Such as, several stromal cells have been employed as treat option for regenerative medicine. For example, human bone marrow-derived stromal cells and adipose-derived stromal cells (ADSCs) are used in cell-based therapy. Data relating to the stem cell therapy and processes associated with ADSC has developed remarkably in the past 10 years. As medical options, both the stromal vascular and ADSC suggests good opportunity as marvelous cell-based therapeutics. The some biological features are the main factors that impact the regenerative activity of ADSCs, including the modulation of the cellular immune system properties and secretion of bioactive proteins such as cytokines, chemokines and growth factors, as well as their intrinsic anti-ulcer and anti-inflammatory potential. A variety of diseases have been treated by ADSCs, and it is not surprising that there has been great interest in the possibility that ADSCs might be used as therapeutic strategy to improve a wider range of diseases. This is especially important when it is remembered that routine therapeutic methods are not completely effective in treat of diseases. Here, it was discuss about applications of ADSC to colitis, liver failure, diabetes mellitus, multiple sclerosis, orthopaedic disorders, hair loss, fertility problems, and salivary gland damage.

Mesenchymal stem/stromal cell extracellular vesicles: From active principle to next generation drug delivery system

It has been demonstrated that the biological effector of mesenchymal stem/stromal cells (MSCs) is their secretome, which is composed of a heterogeneous pool of bioactive molecules, partially enclosed in extracellular vesicles (EVs). Therefore, the MSC secretome (including EVs) has been recently proposed as possible alternative to MSC therapy. The secretome can be considered as a protein-based biotechnological product, it is probably safer compared with living/cycling cells, it presents virtually lower tumorigenic risk, and it can be handled, stored and sterilized as an Active Pharmaceutical/Principle Ingredient (API). EVs retain some structural and technological analogies with synthetic drug delivery systems (DDS), even if their potential clinical application is also limited by the absence of reproducible/scalable isolation methods and Good Manufacturing Practice (GMP)-compliant procedures. Notably, EVs secreted by MSCs preserve some of their parental cell features such as homing, immunomodulatory and regenerative potential. This review focuses on MSCs and their EVs as APIs, as well as DDS, considering their ability to reach inflamed and damaged tissues and to prolong the release of encapsulated drugs. Special attention is devoted to the illustration of innovative therapeutic approaches in which nanomedicine is successfully combined with stem cell therapy, thus creating a novel class of "next generation drug delivery systems."

Heat-stimuli-enhanced osteogenesis using clinically available biomaterials

A recent study reported that heat stress stimulates osteogenesis in an in vivo rat model using alginate gel and magnetite cationic liposomes. However, for clinical use, the efficacy for promoting osteogenesis needs to be investigated using clinically approved materials, and preferably with animals larger than rats. The aim of this study was to evaluate multiple heat stimuli-triggered osteogenesis in rat tibial defect models using already clinically applicable materials (Resovist® and REGENOS®) and determine the efficacy also in the rabbit. Fifty-eight rats and 10 rabbits were divided into two groups, respectively, with or without hyperthermia treatment at 45°C for 15 min. (hyperthermia; 20 rats once a week, 8 rats three times a week, 5 rabbits once a week, control; 30 rats and 5 rabbits). Micro-CT assessment at 4 weeks revealed that a significantly stimulated osteogenesis was observed in the once a week group of both rats and rabbits as compared to the control group (p = 0.018 and 0.036, respectively). In contrast, the three times a week group did not show enhanced osteogenesis. Histological examination and image analysis showed consistent results in which the area of mineralized bone formation in the once a week hyperthermia group was significantly increased compared with that in the control group at four weeks (rat; p = 0.026, rabbit; p = 0.031). Newly formed bone was observed in the grafted materials from the periphery toward the center, and more osteoclasts were found in the once a week group. Heat stress also induced enhanced alkaline phosphatase expression in cultured osteoblastic cells, MC3T3, in vitro (p = 0.03). On the other hand, heat stress had no obvious effects on chondrogenic differentiation using ATDC5 cells. Our study demonstrates that heat-stimuli with clinically applicable novel heating materials can promote significant osteogenesis, and may thus be a promising treatment option for diseases associated with bone defects.

Cytosolic Extract of Human Adipose Stem Cells Reverses the Amyloid Beta-Induced Mitochondrial Apoptosis via P53/Foxo3a Pathway

Human adipose stem cells (hASC) have therapeutic potential for the treatment of neurodegenerative disorders. Mitochondrial dysfunction is frequently observed in most neurodegenerative disorders, including Alzheimer’s disease. We explored the therapeutic potential of hASC cytosolic extracts to attenuate neuronal death induced by mitochondrial dysfunction in an Alzheimer’s disease (AD) in vitro models. Amyloid beta (Aβ) was used to induce cytotoxity in an immortal hippocampal cell line (HT22) and neuronal stem cells from the brain of TG2576 transgenic mice were also used to test the protective role of hASC cytosolic extracts. Cell viability and flow cytometry results demonstrated that the hASC extract prevents the toxicity and apoptosis in AD in vitro models. Moreover, JC-1 and MitoSoxRed staining followed by fluorescence microscopy and flow cytometry results showed that the hASC extract ameliorated the effect of Aβ-induced mitochondrial oxidative stress and reduced the mitochondrial membrane potential. Western blot result showed that hASC extract modulated mitochondria-associated proteins, such as Bax and Bcl2, and down-regulated cleaved caspase-3. In addition, hASC extract decreased Aβ generation and reversed up-regulated p53 and foxo3a protein level in AD in vitro model cell derived from TG2576 mice. Taken together, these findings implicate a protective role of the hASC extract in the Aβ-induced mitochondrial apoptosis via regulation of P53/foxo3a pathway, providing insight into the molecular mechanisms of hASC extract and a therapeutic strategy to ameliorate neuronal death induced by Aβ.

Repair of osteochondral defects in the minipig model by OPF hydrogel loaded with adipose-derived mesenchymal stem cells

AIM

Critical knee osteochondral defects in seven adult minipigs were treated with oligo(polyethylene glycol)fumarate (OPF) hydrogel combined with autologous or human adipose-derived stem cells (ASCs), and evaluated after 6 months.

METHODS

Four defects were made on the peripheral part of right trochleas (n = 28), and treated with OPF scaffold alone or pre-seeded with ASCs.

RESULTS

A better quality cartilage tissue characterized by improved biomechanical properties and higher collagen type II expression was observed in the defects treated by autologous or human ASC-loaded OPF; similarly this approach induced the regeneration of more mature bone with upregulation of collagen type I expression.

CONCLUSION

This study provides the evidence that both porcine and human adipose-derived stem cells associated to OPF hydrogel allow improving osteochondral defect regeneration in a minipig model.

Efficacy of combined therapy of periosteum and bone allograft in a critical-sized defect model in New Zealand white rabbits

Background

Large segmental bone defects caused by trauma, infection, or bone tumor resection are difficult to cure and have been a problem in the field of bone repair for decades. The objective of this study was to discuss the efficacy of combined therapy of free periosteum and bone allograft in treating bone defects and to provide a theoretical basis for clinical application of this therapy.

Material/Methods

A unilateral tibia cortical defect model in New Zealand white rabbits was established according to Girolamo method. Total 48 rabbits were randomized into 3 groups: a simple bone defect group (n=16), an autogenous bone graft group (n=16), and a periosteum and bone allograft combined therapy group (n=16). The efficacy was evaluated by imaging inspections and scoring, HE staining, and RT-PCR in postoperative weeks 2, 4, 8, and 12.

Results

The results of imaging and histopathological inspections in the study indicated that in postoperative weeks 4, 8, and 12 the experimental and control groups had statistically significant differences in Lane-Sandhu radiographic scoring and relative bone density when compared with the simple bone defect group (P<0.05). The RT-PCR results suggested that the expression of SPP-1, BMP-2, and VEGF in the experimental group was higher than in the control group (P<0.05) and the expression of Col Iα1 in the control group was higher than in the experimental group (P<0.05).

Conclusions

Efficacies of the combined therapy (periosteum combined with bone allografting) and the criterion standard therapy (autogenous bone grafting) are equivalent in treating bone defects in New Zealand white rabbits.

Bone marrow mesenchymal stem cells enhance bone formation in orthodontically expanded maxillae in rats

OBJECTIVE

To transplant bone marrow-derived mesenchymal stem cells (MSCs) into the interpremaxillary suture after rapid maxillary expansion with the aim of increasing new bone formation in the suture.

MATERIALS AND METHODS

Nineteen male Wistar rats were divided into two groups (control, n  =  9; experimental, n  =  10). Both groups were subjected to expansion for 5 days, and 50 cN of force was applied to the maxillary incisors with a helical spring. Pkh67(+) (green fluorescent dye)-labeled MSCs were applied to the interpremaxillary suture after force application into the interpremaxillary suture of rats. Bone formation in the sutural area was histomorphometrically evaluated, including the amount of new bone formation (µm(2)), number of osteoblasts, number of osteoclasts, and number of vessels. Mann-Whitney U-test was used for statistical evaluation at the P < .05 level.

RESULTS

After 10 days of retention, Pkh67(+) can be detected in suture mostly in the injection site under fluorescence microscope. Histomorphometric analysis revealed that a single local injection of MSCs into the midpalatal suture increased the new bone formation in the suture by increasing the number of osteoblasts and new vessel formation, compared with controls injected with phosphate-buffered saline.

CONCLUSIONS

This preclinical study might provide foundations for the underlying potential clinical use of MSCs after maxillary expansion. Given the fact that MSCs are currently in use in clinical trials, this approach might be a feasible treatment strategy to accelerate new bone tissue formation in midpalatal suture and to shorten the treatment period for patients undergoing maxillary expansion reinforcement.

Adipose-derived stem cells: a review of signaling networks governing cell fate and regenerative potential in the context of craniofacial and long bone skeletal repair

Improvements in medical care, nutrition and social care are resulting in a commendable change in world population demographics with an ever increasing skew towards an aging population. As the proportion of the world's population that is considered elderly increases, so does the incidence of osteodegenerative disease and the resultant burden on healthcare. The increasing demand coupled with the limitations of contemporary approaches, have provided the impetus to develop novel tissue regeneration therapies. The use of stem cells, with their potential for self-renewal and differentiation, is one potential solution. Adipose-derived stem cells (ASCs), which are relatively easy to harvest and readily available have emerged as an ideal candidate. In this review, we explore the potential for ASCs to provide tangible therapies for craniofacial and long bone skeletal defects, outline key signaling pathways that direct these cells and describe how the developmental signaling program may provide clues on how to guide these cells in vivo. This review also provides an overview of the importance of establishing an osteogenic microniche using appropriately customized scaffolds and delineates some of the key challenges that still need to be overcome for adult stem cell skeletal regenerative therapy to become a clinical reality.

Adipose stromal/stem cells assist fat transplantation reducing necrosis and increasing graft performance

Autologous fat transfer (AFT) is a procedure for adipose tissue (AT) repair after trauma, burns, post-tumor resections and lipodystrophies still negatively impacted by the lack of graft persistence. The reasons behind this poor outcome are unclear and seem to involve damages in either harvested/transplanted mature adipocytes or on their mesenchymal progenitors, namely adipose stromal/stem cells (ASC), and due to post-transplant AT apoptosis and involution. A rabbit subcutaneous AT regeneration model was here developed to first evaluate graft quality at different times after implant focusing on related parameters, such as necrosis and vasculogenesis. Standard AFT was compared with a strategy where purified autologous ASC, combined with hyaluronic acid (HA), assisted AFT. Five million of autologous ex vivo isolated CD29+, CD90+, CD49e+ ASC, loaded into HA, enriched 1 ml of AT generating an early significant protective effect in reducing AFT necrosis and increasing vasculogenesis with a preservation of transplanted AT architecture. This beneficial impact of ASC assisted AFT was then confirmed at three months with a robust lipopreservation and no signs of cellular transformation. By a novel ASC assisted AFT approach we ensure a reduction in early cell death favoring an enduring graft performance possibly for a more stable benefit in patients.

Suitability of autologous serum for expanding rabbit adipose-derived stem cell populations

Adipose-derived stem cells (ASCs) are believed to have potential use for treating many illnesses. Most cells, including ASCs, are generally cultured in medium containing fetal bovine serum (FBS). However, FBS, which could induce an immune response or infection, is not recommended for clinical applications. In the present study, we evaluated the morphology, proliferation rate, and characterization of rabbit ASCs grown in medium containing autologous serum (AS) and compared these cells to ones cultured with FBS. Morphological changes were monitored by microscopy and flow cytometry. Proliferation rates were assessed with cell counting and ASC phenotypes were characterized by flow cytometry using representative surface markers (CD44 and CD45). Expression of epidermal growth factor, brain-derived neurotrophic factor, and vascular endothelial growth factor was measured by reverse transcription-polymerase chain reaction. Results of our study showed that ASCs had a greater expansion rate in AS without developing morphological heterogeneity than cells grown in FBS. AS-cultured ASCs expressed representative growth factors, CD44 but not CD45, similar to cells cultured in FBS. Expression levels of some growth factors were different between AS and FBS. In conclusion, our findings indicated that AS could potentially be used as a culture medium supplement for the expansion of autologous ASCs.

Critical size bone defect reconstruction by an autologous 3D osteogenic-like tissue derived from differentiated adipose MSCs

For critical size bone defects and bone non-unions, bone tissue engineering using osteoblastic differentiated adipose mesenchymal stem cells (AMSCs) is limited by the need for a biomaterial to support cell transplantation. An osteoblastic three-dimensional autologous graft made of AMSCs (3D AMSC) was developed to solve this issue. This autograft was obtained by supplementing the osteoblastic differentiation medium with demineralized bone matrix. Two surgical models were developed to assess the potential of this 3D osteogenic AMSC autograft. A four-level spinal fusion using polyetheretherketone cages was designed in six pigs to assess the early phase of ossification (8-12 weeks postimplantation). In each pig, four groups were compared: cancellous bone autograft, freeze-dried irradiated cancellous pig bone, 3D AMSC, and an empty cage. A critical size femoral defect (n = 4, bone non-union confirmed 6 months postoperatively) was used to assess the 3D AMSCs' ability to achieve bone fusion. Pigs were followed by CT scan and explanted specimens were analyzed for bone tissue remodeling by micro-CT scan, micro-radiography, and histology/histomorphometry. In the spine fusion model, bone formation with the 3D AMSC was demonstrated by a significant increase in bone content. In the critical-size femoral defect model, the 3D AMSC achieved new bone formation and fusion in a poorly vascularized fibrotic environment. This custom-made 3D osteogenic AMSC autograft is a therapeutic solution for bone non-unions and for critical-size defects.

Adipose-derived stem cells and rabbit bone regeneration: histomorphometric, immunohistochemical and mechanical characterization

BACKGROUND

In the last few years, several attempts have been made to treat large bone loss, including the use of tissue engineering with osteoinductive scaffolds and cells. This study highlights the role of mesenchymal stem cells from adipose tissue (ASCs; adipose-derived stem cells) in a rabbit bone regeneration model.

METHODS

We compared the neoformed bone tissues achieved by treating critical tibial defects with either hydroxyapatite alone (HA, group I) or hydroxyapatite-autologous ASC constructs (ASCs-HA, group II), investigating their histomorphometric, immunohistochemical and biomechanical properties.

RESULTS

After eight weeks of follow-up, we observed advanced maturation and a spatial distribution of new bone that was more homogeneous in the inner parts of the pores in group II, not just along the walls (as seen in group I). The new tissue expressed osteogenic markers, and biomechanical tests suggested that the newly formed bone in group II had a higher mineral content than that in group I. Although variability in differentiation was observed among the different cell populations in vitro, no differences in bone healing were observed in vivo; the variability seen in vitro was probably due to local microenvironment effects.

CONCLUSIONS

Tibial defects treated with rabbit ASCs-HA showed an improved healing process when compared to the process that occurred when only the scaffold was used. We suggest that implanted ASCs ameliorate the bone reparative process either directly or by recruiting resident progenitor cells.

Chemical and genetic blockade of HDACs enhances osteogenic differentiation of human adipose tissue-derived stem cells by oppositely affecting osteogenic and adipogenic transcription factors

The human adipose-tissue derived stem/stromal cells (hASCs) are an interesting source for bone-tissue engineering applications. Our aim was to clarify in hASCs the role of acetylation in the control of Runt-related transcription factor 2 (Runx2) and Peroxisome proliferator activated receptor (PPAR) γ. These key osteogenic and adipogenic transcription factors are oppositely involved in osteo-differentiation. The hASCs, committed or not towards bone lineage with osteoinductive medium, were exposed to HDACs chemical blockade with Trichostatin A (TSA) or were genetically silenced for HDACs. Alkaline phosphatase (ALP) and collagen/calcium deposition, considered as early and late osteogenic markers, were evaluated concomitantly as index of osteo-differentiation. TSA pretreatment, useful experimental protocol to analyse pan-HDAC-chemical inhibition, and switch to osteogenic medium induced early-osteoblast maturation gene Runx2, while transiently decreased PPARγ and scarcely affected late-differentiation markers. Time-dependent effects were observed after knocking-down of HDAC1 and 3: Runx2 and ALP underwent early activation, followed by late-osteogenic markers increase and by PPARγ/ALP activity diminutions mostly after HDAC3 silencing. HDAC1 and 3 genetic blockade increased and decreased Runx2 and PPARγ target genes, respectively. Noteworthy, HDACs knocking-down favoured the commitment effect of osteogenic medium. Our results reveal a role for HDACs in orchestrating osteo-differentiation of hASCs at transcriptional level, and might provide new insights into the modulation of hASCs-based regenerative therapy.

Neuroprotective effects of adipose-derived stem cells against ischemic neuronal damage in the rabbit spinal cord

Transplantation of adipose-derived stem cells (ASCs) is one of the possible therapeutic tools for ischemic damage. In this study, we observed the effects of ASCs against ischemic damage in the ventral horn of L(5-6) levels in the rabbit spinal cord. ASCs were isolated from rabbits, and cell type was confirmed by flow cytometry analysis, labeling with CM-DiI dye and differentiation into adipocytes in adipogenesis differentiation medium. ASCs were administered intrathecally into recipient rabbits (2 × 10⁵) immediately after reperfusion following a 15-min aortic artery occlusion in the subrenal region. Transplantation of ASCs significantly improved functions of the hindlimb and morphology of the ventral horn of spinal cord although CM-DiI-labeled ASCs were not observed in the spinal cord parenchyma. In addition, transplantation of ASCs significantly increased brain-derived neurotrophic factor (BDNF) levels at 72h after ischemia/reperfusion. These results suggest that transplantation of ASCs prevents motor neurons from spinal ischemic damage and reactive gliosis by increasing neurotrophic factors such as BDNF in the spinal cord.