Isolation, characterization and osteogenic differentiation of adipose-derived stem cells: from small to large animal models

Effect of in vivo culture conditions on the proliferation and differentiation of rat adipose-derived stromal cells

Adipose-derived stromal cells (ADSCs) are promising stem cell sources for tissue engineering and cell-based therapy. However, long-term in vitro expansion of ADSCs impedes stemness maintenance, which is partly attributed to deprivation of their original microenvironment. Incompetent cells limit the therapeutic effects of ADSC-based clinical strategies. Therefore, reconstructing a more physiologically and physically relevant niche is an ideal strategy to address this issue and therefore facilitates the extensive application of ADSCs. Here, we transplanted separated ADSCs into local subcutaneous adipose tissues of nude mice as an in vivo cell culture model. We found that transplanted ADSCs maintained their primitive morphology and showed improved proliferation and delayed senescence compared to those of cells cultured in an incubator. Significantly increased expression of stemness-related markers and multilineage differentiation abilities were further observed in in vivo cultured ADSCs. Finally, sequencing revealed that genes whose expression differed between ADSCs obtained under in vivo and in vitro conditions were mainly located in the extracellular matrix and extracellular space and that these genes participate in regulating transcription and protein synthesis. Moreover, we found that an Egr1 signaling pathway might exert a crucial impact on controlling stemness properties. Our findings might collectively pave the way for ADSC-based applications.

Trends of regenerative tissue engineering for oral and maxillofacial reconstruction in veterinary medicine

Oral and maxillofacial (OMF) defects are not limited to humans and are often encountered in other species. Reconstructing significant tissue defects requires an excellent strategy for efficient and cost-effective treatment. In this regard, tissue engineering comprising stem cells, scaffolds, and signaling molecules is emerging as an innovative approach to treating OMF defects in veterinary patients. This review presents a comprehensive overview of OMF defects and tissue engineering principles to establish proper treatment and achieve both hard and soft tissue regeneration in veterinary practice. Moreover, bench-to-bedside future opportunities and challenges of tissue engineering usage are also addressed in this literature review.

Effects of Oral Cavity Stem Cell Sources and Serum-Free Cell Culture on Hydrogel Encapsulation of Mesenchymal Stem Cells for Bone Regeneration: An In Vitro Investigation

INTRODUCTION

To develop a stem cell delivery model and improve the safety of stem cell transplantation for bone regeneration, this study aimed to determine the effects of stem cell sources, serum-free cell culture, and hydrogel cell encapsulation on the growth and osteogenic differentiation of mesenchymal stem cells (MSCs) from the oral cavity.

METHODS

The study groups were categorized according to stem cell sources into buccal fat pad adipose (hBFP-ADSCs) (Groups 1, 4, and 7), periodontal ligament (hPDLSCs) (Groups 2, 5, and 8), and dental pulp-derived stem cells (hDPSCs) (Groups 3, 6, and 9). MSCs from each source were isolated and expanded in three types of sera: fetal bovine serum (FBS) (Groups 1-3), human serum (HS) (Groups 4-6), and synthetic serum (SS) (StemPro™ MSC SFM) (Groups 7-9) for monolayer (m) and hydrogel cell encapsulation cultures (e). Following this, the morphology, expression of MSC cell surface antigens, growth, and osteogenic differentiation potential of the MSCs, and the expression of adhesion molecules were analyzed and compared.

RESULTS

SS decreased variations in the morphology and expression levels of cell surface antigens of MSCs from three cell sources (Groups 7m-9m). The levels of osteoblastic differentiation of the hPDLSCs and hBFP-ADSCs were increased in SS (Groups 8m and 7m) and the cell encapsulation model (Groups 1e, 4e, 7e-9e), but the promoting effects of SS were decreased in a cell encapsulation model (Groups 7e-9e). The expression levels of the alpha v beta 3 (ITG-αVβ3) and beta 1 (ITG-β1) integrins in the encapsulated cells in FBS (Group 1e) were higher than those in the SS (Group 7e).

CONCLUSIONS

Human PDLSCs and BFP-ADSCs were the optimum stem cell source for stem cell encapsulation by using nanohydroxyapatite-calcium carbonate microcapsule-chitosan/collagen hydrogel in serum-free conditions.

Influence of the Anatomical Site on Adipose Tissue-Derived Stromal Cells' Biological Profile and Osteogenic Potential in Companion Animals

Adipose tissue-derived stromal cells (ADSCs) have generated considerable interest in the field of veterinary medicine, particularly for their potential in therapeutic strategies focused on bone regeneration. These cells possess unique biological characteristics, including their regenerative capacity and their ability to produce bioactive molecules. However, it is crucial to recognize that the characteristics of ADSCs can vary depending on the animal species and the site from which they are derived, such as the subcutaneous and visceral regions (SCAT and VAT, respectively). Thus, the present work aimed to comprehensively review the different traits of ADSCs isolated from diverse anatomical sites in companion animals, i.e., dogs, cats, and horses, in terms of immunophenotype, morphology, proliferation, and osteogenic differentiation potential. The findings indicate that the immunophenotype, proliferation, and osteogenic potential of ADSCs differ according to tissue origin and species. Generally, the proliferation rate is higher in VAT-derived ADSCs in dogs and horses, whereas in cats, the proliferation rate appears to be similar in both cells isolated from SCAT and VAT regions. In terms of osteogenic differentiation potential, VAT-derived ADSCs demonstrate the highest capability in cats, whereas SCAT-derived ADSCs exhibit superior potential in horses. Interestingly, in dogs, VAT-derived cells appear to have greater potential than those isolated from SCAT. Within the VAT, ADSCs derived from the falciform ligament and omentum show increased osteogenic potential, compared to cells isolated from other anatomical locations. Consequently, considering these disparities, optimizing isolation protocols becomes pivotal, tailoring them to the specific target species and therapeutic aims, and judiciously selecting the anatomical site for ADSC isolation. This approach holds promise to enhance the efficacy of ADSCs-based bone regenerative therapies.

Osteogenic differentiation of adipose-derived canine mesenchymal stem cells seeded in porous calcium-phosphate scaffolds

Introduction

Engineered bone graft substitutes are a promising alternative and supplement to autologous bone grafts as treatments for bone healing impairment. Advances in human medicine extend an invitation to pursue these biomimetic strategies in animal patients, substantiated by the theory that specialized scaffolds, multipotent cells, and biological cues may be combined into a bioactive implant intended for the enhancement of tissue regeneration.

Methods

This proof-of-concept study was designed to evaluate and validate the feasibility of beta-tricalcium phosphate foam scaffolds seeded with canine mesenchymal stem cells derived from adipose tissue. Cell-inoculated samples and sham controls were cultured statically for 72 hours in complete growth medium to evaluate seeding capacity, while a subset of loaded scaffolds was further induced with osteogenic culture medium for 21 days. Produced implants were characterized and validated with a combination of immunofluorescence and reflection confocal microscopy, scanning electron microscopy, and polymerase chain reaction to confirm osteogenic differentiation in tridimensional-induced samples.

Results

After 72 hours of culture, all inoculated scaffolds presented widespread yet heterogeneous surface seeding, distinctively congregating stem cells around pore openings. Furthermore, at 21 days of osteogenic culture conditions, robust osteoblastic differentiation of the seeded cells was confirmed by the change of cell morphology and evident deposition of extra-cellular matrix, accompanied by mineralization and scaffold remodeling; furthermore, all induced cell-loaded implants lost specific stemness immunophenotype expression and simultaneously upregulated genomic expression of osteogenic genes Osterix and Ostecalcin.

Conclusions

β-TCP bio-ceramic foam scaffolds proved to be suitable carriers and hosts of canine adipose-derived MSCs, promoting not only surface attachment and proliferation, but also demonstrating strong in-vitro osteogenic potential. Although this research provides satisfactory in-vitro validation for the conceptualization and feasibility of a canine bio-active bone implant, further testing such as patient safety, large-scale reproducibility, and quality assessment are needed for regulatory compliance in future commercial clinical applications.

Impact of Adipose Tissue Depot Harvesting Site on the Multilineage Induction Capacity of Male Rat Adipose-Derived Mesenchymal Stem Cells: An In Vitro Study

Recently, substantial attention has been paid toward adipose-derived mesenchymal stem cells (AdMSCs) as a potential therapy in tissue engineering and regenerative medicine applications. Rat AdMSCs (r-AdMSCs) are frequently utilized. However, the influence of the adipose depot site on the multilineage differentiation potential of the r-AdMSCs is still ambiguous. Hence, the main objective of this study was to explore the influence of the adipose tissue harvesting location on the ability of r-AdMSCs to express the stem-cell-related markers and pluripotency genes, as well as their differentiation capacity, for the first time. Herein, we have isolated r-AdMSCs from the inguinal, epididymal, peri-renal, and back subcutaneous fats. Cells were compared in terms of their phenotype, immunophenotype, and expression of pluripotency genes using RT-PCR. Additionally, we investigated their potential for multilineage (adipogenic, osteogenic, and chondrogenic) induction using special stains confirmed by the expression of the related genes using RT-qPCR. All cells could positively express stem cell marker CD 90 and CD 105 with no significant in-between differences. However, they did not express the hematopoietic markers as CD 34 and CD 45. All cells could be induced successfully. However, epididymal and inguinal cells presented the highest capacity for adipogenic and osteogenic differentiation (21.36-fold and 11.63-fold for OPN, 29.69-fold and 26.68-fold for BMP2, and 37.67-fold and 22.35-fold for BSP, respectively, in epididymal and inguinal cells (p < 0.0001)). On the contrary, the subcutaneous cells exhibited a superior potential for chondrogenesis over the other sites (8.9-fold for CHM1 and 5.93-fold for ACAN, (p < 0.0001)). In conclusion, the adipose tissue harvesting site could influence the differentiation capacity of the isolated AdMSCs. To enhance the results of their employment in various regenerative cell-based therapies, it is thus vital to take the collection site selection into consideration.

Retinoic acid induces the osteogenic differentiation of cat adipose tissue-derived stromal cells from distinct anatomical sites

Mesenchymal stromal cells-based regenerative orthopedic therapies have been used in cats as a promising and innovative therapeutic approach to enhance the repair of bone defects. Adipose tissue-derived stromal cells (ADSCs) can be obtained from two main sites-subcutaneous and visceral-with established differences regarding structure, composition, cell content, and functionality. However, in cats, to the best of the authors' knowledge, no studies have been conducted to compare the functional activity of the ADSCs isolated from the two sites, and the impact of these differences on the induced osteogenic potential. Additionally, retinoic acid has been recently regarded as a new osteogenic inducer within cells of distinct species, with undisclosed functionality on cat-derived cell populations. Thus, the present study aimed to evaluate the functional activity of ADSCs isolated from the subcutaneous and visceral adipose sites (SCAT and VAT, respectively) of the cat, as well as the effects of two osteogenic-inducing conditions-the classic dexamethasone, β-glycerophosphate and ascorbic acid-supplemented media (Dex + β + AAM), and Retinoic Acid-supplemented media (RAM). The adipose tissue of subcutaneous and visceral origin was isolated, characterized, and ADSCs were isolated and grown in the presence of the two osteogenic-inducing conditions, and characterized in terms of proliferation, metabolic activity, morphology, and osteogenic activity. Our results demonstrated a distinct biological profile of the two adipose tissue sites regarding cell size, vascularization, and morphology. Further, osteogenic-induced ADSCs from both sites presented an increased expression of alkaline phosphatase activity (ALP) and cytochemical staining, as compared with control. Overall, RAM induced higher levels of ALP activity than Dex + β + AAM, supporting an increased osteogenic activation. Additionally, VAT was the tissue with the best osteogenic potential, showing higher levels of ALP expression, particularly with RAM. In conclusion, different characteristics were found between the two adipose tissue sites-SCAT and VAT, which probably reflect the differences found in the functionality of isolated ADSCs from both tissues. Furthermore, for cat, VAT shows a greater osteogenic-inductive capacity than SCAT, particularly with RAM, which can be of therapeutic relevance for regenerative medicine applications.

The Osteogenic Potential of Falciform Ligament-Derived Stromal Cells-A Comparative Analysis between Two Osteogenic Induction Programs

Mesenchymal stromal cells (MSCs) have gained special relevance in bone tissue regenerative applications. MSCs have been isolated from different depots, with adipose tissue being acknowledged as one of the most convenient sources, given the wide availability, high cellular yield, and obtainability. Recently, the falciform ligament (FL) has been regarded as a potential depot for adipose tissue-derived stromal cells (FL-ADSCs) isolation. Nonetheless, the osteogenic capability of FL-ADSCs has not been previously characterized. Thus, the present study aimed the detailed characterization of FL-ADSCs' functionality upon osteogenic induction through a classic (dexamethasone-based-DEX) or an innovative strategy with retinoic acid (RA) in a comparative approach with ADSCs from a control visceral region. Cultures were characterized for cell proliferation, metabolic activity, cellular morphology, fluorescent cytoskeletal and mitochondrial organization, and osteogenic activity-gene expression analysis and cytochemical staining. FL-derived populations expressed significantly higher levels of osteogenic genes and cytochemical markers, particularly with DEX induction, as compared to control ADSCs that were more responsive to RA. FL-ADSCs were identified as a potential source for bone regenerative applications, given the heightened osteogenic functionality. Furthermore, data highlighted the importance of the selection of the most adequate osteogenic-inducing program concerning the specificities of the basal cell population.

Potential renal stem/progenitor cells identified by in vivo lineage tracing

Mammalian kidneys consist of more than 30 different types of cells. A challenging task is to identify and characterize the stem/progenitor subpopulations that establish the lineage relationships among these cellular elements during nephrogenesis in the embryonic and neonate kidneys and during tissue homeostasis and/or injury repair in the mature kidney. Moreover, the potential clinical utility of stem/progenitor cells holds promise for development of new regenerative medicine approaches for the treatment of renal diseases. Stem cells are defined by unlimited self-renewal capacity and pluripotentiality. Progenitor cells have pluripotentiality, but no or limited self-renewal potential. Cre-LoxP-based in vivo genetic lineage tracing is a powerful tool to identify the stem/progenitor cells in their native environment. Hypothetically, this technique enables investigators to accurately track the progeny of a single cell, or a group of cells. The Cre/loxP system has been widely employed to uncover the function of genes in various mammalian tissues and to identify stem/progenitor cells through in vivo lineage tracing analyses. In this review, we summarize the recent advances in the development and characterization of various Cre drivers, and their use in identifying potential renal stem/progenitor cells in both developing and mature mouse kidneys.

Enhanced Bone Formation in Osteoporotic Mice by a Novel Transplant Combined with Adipose-derived Stem Cells and Platelet-rich Fibrin Releasates

Osteoporotic fracture is the main complication of osteoporosis (OP) and accounts for millions of injuries annually. Local intervention by intra-marrow injection has been a good option for preventing osteoporotic bone loss when the osteoporotic femoral fracture has been treated. In this study, tail vein transplantations were examined to evaluate the cell-based therapeutic approach for treating OP with adipose-derived stem cells (ADSCs) and platelet-rich fibrin releasates (PRFr) in an ovariectomized (OVX) mice model. Thirty-six 12-wk-old female ICR mice were randomly divided into six groups: untreated control; sham-operated; OVX-control; OVX-ADSCs; OVX-PRFr; and OVX-ADSCs+PRFr. Starting 8 wk after ovariectomy, the OVX mice received tail vein injections once each week for four consecutive weeks, then were evaluated radiographically and histopathologically 8 wk after the first injection. We also assessed changes to bone trabeculae in the proximal tibial growth plate. In OVX mice treated with ADSCs or PRFr alone, or with a combination of ADSCs and PRFr, the trabecular bone mineral density (BMD), bone volume ratios (BV/TV), and numbers (Tb.N) in the proximal tibia areas were significantly higher than that in the OVX-control group. Significant differences between OVX-treated mice and OVX controls were found for trabecular separation, but not for trabecular thickness. These results indicate that ADSCs or PRFr treatment enhances bone microarchitecture in OP. The treatment of bone loss of OVX mice with ADSCs+PRFr induced greater bone consolidation with bone tissue production (P < 0.01) when compared to the others. Thus, we conclude that the transplantation of ADSCs combined with PRFr might provide an alternative strategy for the treatment of various bone disorders in OP with an unlimited source of cells and releasates.

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.

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.

•

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.

•

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

Adipose-Derived Stromal/Stem Cells from Large Animal Models: from Basic to Applied Science

Adipose-derived stem cells (ASCs) isolated from domestic animals fulfill the qualitative criteria of mesenchymal stem cells, including the capacity to differentiate along multiple lineage pathways and to self-renew, as well as immunomodulatory capacities. Recent findings on human diseases derived from studying large animal models, have provided evidence that administration of autologous or allogenic ASCs can improve the process of healing. In a narrow group of large animals used in bioresearch studies, pigs and horses have been shown to be the best suited models for study of the wound healing process, cardiovascular and musculoskeletal disorders. To this end, current literature demonstrates that ASC-based therapies bring considerable benefits to animal health in both spontaneously occurring and experimentally induced clinical cases. The purpose of this review is to provide an overview of the diversity, isolation, and characterization of ASCs from livestock. Particular attention has been paid to the functional characteristics of the cells that facilitate their therapeutic application in large animal models of human disease. In this regard, we describe outcomes of ASCs utilization in translational research with pig and horse models of disease. Furthermore, we evaluate the current status of ASC-based therapy in veterinary practice, particularly in the rapidly developing field of equine regenerative medicine. In conclusion, this review presents arguments that support the relevance of animal ASCs in the field of regenerative medicine and it provides insights into the future perspectives of ASC utilization in animal husbandry.

Magnetic targeting of super-paramagnetic iron oxide nanoparticle labeled myogenic-induced adipose-derived stem cells in a rat model of stress urinary incontinence

Cell-based injectable therapy utilizing stem cells is a promising approach for the treatment of stress urinary incontinence (SUI). Applying a magnetically controlled cell delivery approach has enormous potential to enhance cell retention capability within the specified site. To assess the therapeutic efficacy of cellular magnetic targeting, we applied an external magnetic force to target an adipose-derived stem cell based therapy in a rat model of SUI. The results revealed that magnetic attraction of transplanted cells under the magnetic field was generated by cell uptake of superparamagnetic iron oxide nanoparticles in vitro. More importantly, magnetic targeting improved the retention rate of transplanted cells and facilitated the restoration of sphincter structure and function in a rat SUI model according to the results of histological examination and urodynamic testing. Therefore, magnetically guided targeting strategy might be a potential therapy method for treatment of SUI.

Efficient isolation and proliferation of human adipose-derived mesenchymal stromal cells in xeno-free conditions

Classical methods used for culture of adipose-derived mesenchymal stromal cells (ADSCs) use xenobiotic components, which may present a potential risk for biological contamination and/or elicit immunological reactions. Therefore, the aim of this study was to establish a xeno-free methodology for the isolation and proliferation of human ADSCs (hADSCs). hADSCs were isolated by enzymatic digestion or mechanical dissociation and cultured in the presence of fetal bovine serum or human platelet lysate. Proliferation curves were performed as a function of time from the cell culture and used to calculate the population doubling time. Immunophenotyping and differentiation tests were used to identify and characterize the hADSCs. Human ADSCs isolated and cultured in conventional or xenobiotic-free conditions peaked at different days but achieved similar maximum proliferation. The hADSCs differentiation ability was similar in all groups. The characterization of hADSCs by flow cytometry showed low contamination of the cultures by other cell types. The xenobiotic-free methodology described in this study is a feasible and reproducible alternative for isolation and proliferation of hADSCs. This methodology is in accordance with the recommendations of the National Health Surveillance Agency, which proposes avoidance of xenobiotic products.

Co-culture of mesenchymal stem cells and human umbilical vein endothelial cells on heparinized polycaprolactone/gelatin co-spun nanofibers for improved endothelium remodeling

Endothelization of a tissue-engineered substrate is important for its application as an artificial vascular graft. Despite recent advancements in artificial graft fabrication, a graft of <5 mm is difficult to fabricate owing to insufficient endothelization that results in thrombosis after transplantation. We aimed to perform a co-culture of adipose-derived mesenchymal stem cells (MSCs) with human umbilical vein endothelial cells (HUVECs) on antithrombogenic polycaprolactone (PCL)/heparin-gelatin co-spun nanofibers to evaluate the role of co-culturing in promoting quick endothelization of vascular substrates without surface modification by growth factors or other ECM proteins that trigger the endothelization process. Using a co-axial electrospinning technique, we attempted to fabricate our scaffold balancing between mechanical properties and biocompatibility. Antithrombogenic characteristics were then imparted to the fabricated nanofiber substrate by grafting of heparin. Finally, we performed a co-culture of MSCs and HUVECs on the fabricated co-spun nanofiber substrate to obtain proper endothelization of our material under the in-vitro culture. Staining for CD-31 at seven days of culture revealed enhanced CD-31 expression under the co-culture condition; actin staining revealed healthy cobblestone HUVEC morphology, suggesting that MSCs can aid in proper endothelization. Hence, we conclude that co-culture is effective for quick endothelization of vascular substrates.

Development of dual delivery antituberculotic system containing rifapentine microspheres and adipose stem cells seeded in hydroxyapatite/tricalcium phosphate

Background

Low drug concentration in the tuberculosis (TB) lesion and bone defects or nonunion after debridement are two major problems that occur in the course of treating osteo-articular TB. Thus, the combination of drug-delivery system and bone tissue repair appears to be the most promising option for osteoarticular TB treatment.

Materials and methods

Herein, we report a novel anti-TB dual delivery system based on rifapentine polylactic acid microspheres (RPMs) to treat infections, with the addition of adipose-derived mesenchymal stem cells (ASCs) seeded in hydroxyapatite/tricalcium phosphate (HA/TCP) to promote bone formation. Cell proliferation, osteogenesis, and apoptosis were performed to investigate the effects of rifapentine on ASCs. The RPMs were synthesized by emulsion-solvent evaporation method, and then the monolayer composite (ASC + RPM) and three-dimensional (3D) composite scaffold (ASC + RPM + HA/TCP) were constructed, respectively. The alkaline phosphatase (ALP) activity and real-time PCR were used for determining the osteogenic differentiation. The concentrations of rifapentine resulting from the composites were detected.

Results

The results showed that rifapentine has no influence on ASCs proliferation and osteogenesis when the drug concentration was below 20 µg/mL, which was significantly higher than minimal inhibitory concentration. The drug loading and encapsulation efficiency of RPMs were 40.56%±2.63% and 70.24%±2.18%, respectively. The proliferation of the cells in monolayer was higher than that in 3D composite, and the addition of RPMs slightly increased the proliferation. The ALP activity and gene expression of osteocalcin and osteopontin were higher in the 3D composite than those in the monolayer. Good biocompatibility was observed by microscopic image and H&E stain. The release tests revealed that the 3D composite exhibited sustained release profiles of rifapentine for 76 days. The dual delivery systems in 3D composite could moderate the burst release and extend the length of release time when compared to single delivery in monolayers.

Conclusion

In conclusion, such dual delivery antituberculotic scaffold represents a potential new strategy for TB infections and bone defects.

Comparison of the regenerative effect of adipose-derived stem cells, fibrin glue scaffold, and autologous bone graft in experimental mandibular defect in rabbit

BACKGROUND/AIMS

One of the main concerns for maxillofacial and orthopedic surgeons is finding a method to improve regeneration of large craniofacial bone defects. The aim of this study was to investigate the healing and regenerative effects of fibrin glue associated with adipose-derived stem cells (ADSCs) and fibrin glue scaffold alone with autologous bone grafts in experimental mandibular defects of the rabbit.

METHODS

Bilateral uni-cortical osteotomies were performed in the mandible of 20 male Dutch rabbits. The animals were randomly divided into 2 equal groups. In one group, the defect on the right side was treated by fibrin glue associated with ADSCs and the defect on the other side remained as the control. In another group, the defect on the right side was treated with fibrin glue and on the left side with autologous bone graft. After 28 and 56 days, five rabbits from each group were evaluated by computed tomography (CT) and histopathological examinations.

RESULTS

Coronal CT showed a remarkable reconstruction of cortical bone in the fibrin glue associated with ADSCs group at 28 and 56 days post-surgery. Histopathologically, new cortical bony bridge formation was seen increasingly in the fibrin glue, fibrin glue associated with ADSCs, and autologous bone graft groups after 28 days. Statistical analysis of the thickness of new cortical bone in the treatment versus control groups showed a significant difference between fibrin glue alone and fibrin glue associated with ADSCs groups (P = 0.02). No significant difference was found between the fibrin glue associated with ADSCs and the autologous bone graft groups (P > 0.05).

CONCLUSIONS

The healing process had a significant increase in the thickness of new cortical bone when fibrin glue scaffold associated with ADSCs was used.

A Thin Layer of Decellularized Porcine Myocardium for Cell Delivery

Decellularized porcine myocardium has shown many benefits as a cell delivery scaffold for cardiac therapy. However, using full thickness decellularized myocardium as cardiac patch may lead to poor viability and inhomogeneous distribution of delivered cells, due to perfusion limitations. In this study, we explored the feasibility of decellularized porcine myocardial slice (dPMS) to construct a vascularized cardiac patch for cell delivery. Decellularized porcine myocardium was sliced into thin layers (thickness~300 µm). Adipose-derived Stem cells (ASCs) obtained from rat and pig were seeded on dPMS. The viability, infiltration, and differentiation of seeded ASCs were examined. The mechanical properties of dPMSs of various thickness and native myocardium were tested. We noticed dPMS supported attachment and growth of rat and pig ASCs. Both rat and pig ASCs showed high viability, similar patterns of proliferation and infiltration within dPMS. Rat ASCs showed expression of early-endothelial markers followed by mature-endothelial marker without any additional inducers on dPMS. Using rat myocardial infarction model, we delivered ASCs using dPMS patched to the infarcted myocardium. After 1 week, a higher number of transplanted cells were present in the infarcted area when cells were delivered using dPMS versus direct injection. Compared with MI group, increased vascular formation was also observed.

Distinct features of rabbit and human adipose-derived mesenchymal stem cells: implications for biotechnology and translational research

Introduction

Owing to their similarity with humans, rabbits are useful for multiple applications in biotechnology and translational research from basic to preclinical studies. In this sense, mesenchymal stem cells (MSCs) are known for their therapeutic potential and promising future in regenerative medicine. As many studies have been using rabbit adipose-derived MSCs (ASCs) as a model of human ASCs (hASCs), it is fundamental to compare their characteristics and understand how distinct features could affect the translation to human medicine.

Objective

The aim of this study was to comparatively characterize rabbit ASCs (rASCs) and hASCs to further uses in biotechnology and translational studies.

Materials and methods

rASCs and hASCs were isolated and characterized by their immunophenotype, differentiation potential, proliferative profile, and nuclear stability in vitro.

Results and discussion

Both ASCs presented differentiation potential to osteocytes, chondrocytes, and adipocytes and shared similar immunophenotype expression to CD105+, CD34−, and CD45−, but rabbit cells expressed significantly lower CD73 and CD90 than human cells. In addition, rASCs presented greater clonogenic potential and proliferation rate than hASCs but no difference in nuclear alterations.

Conclusion

The distinct features of rASCs and hASCs can positively or negatively affect their use for different applications in biotechnology (such as cell reprogramming) and translational studies (such as cell transplantation, tissue engineering, and pharmacokinetics). Nevertheless, the particularities between rabbit and human MSCs should not prevent rabbit use in preclinical models, but care should be taken to interpret results and properly translate animal findings to medicine.

Revisiting the Advances in Isolation, Characterization and Secretome of Adipose-Derived Stromal/Stem Cells

Adipose-derived stromal/stem cells (ASCs) seems to be a promising regenerative therapeutic agent due to the minimally invasive approach of their harvest and multi-lineage differentiation potential. The harvested adipose tissues are further digested to extract stromal vascular fraction (SVF), which is cultured, and the anchorage-dependent cells are isolated in order to characterize their stemness, surface markers, and multi-differentiation potential. The differentiation potential of ASCs is directed through manipulating culture medium composition with an introduction of growth factors to obtain the desired cell type. ASCs have been widely studied for its regenerative therapeutic solution to neurologic, skin, wound, muscle, bone, and other disorders. These therapeutic outcomes of ASCs are achieved possibly via autocrine and paracrine effects of their secretome comprising of cytokines, extracellular proteins and RNAs. Therefore, secretome-derivatives might offer huge advantages over cells through their synthesis and storage for long-term use. When considering the therapeutic significance and future prospects of ASCs, this review summarizes the recent developments made in harvesting, isolation, and characterization. Furthermore, this article also provides a deeper insight into secretome of ASCs mediating regenerative efficacy.

CD105+ Porcine Endometrial Stromal Mesenchymal Stem Cells Possess Differentiation Potential Toward Cardiomyocyte-Like Cells and Insulin-Producing β Cell-Like Cells In Vitro

Porcine mesenchymal stem cells (MSCs) are similar to human MSCs, hence considered a valuable model for assessing potential for cell therapy. Porcine adipose-derived MSCs (AD-MSCs) and endometrial stromal MSCs (EMSCs) displayed fibroblast-like morphology and were positive for MSC markers CD73, CD90, and CD105 and negative for hematopoietic markers CD34 and CD45. The EMSCs had similar or slightly higher growth rate compared to AD-MSCs, and similar percentage of cells of both EMSCs and AD-MSCs were at G0/G1 and G2/M phases; however, EMSCs had significantly ( P < .05) higher percentage of cells at S phase of cell cycle than AD-MSCs. Transdifferentiation ability to cardiomyocyte-like cells was confirmed in differentiated cells by the expression of lineage-specific marker genes such as DES, ACTA2, cTnT, and ACTC1 by real-time quantitative polymerase chain reaction (RT-qPCR). Furthermore, cardiomyocyte-specific protein markers cTnT and ACTC1 were expressed in completely differentiated cells. Endodermal differentiation capacity of EMSCs to pancreatic β cell-like cells was evident with the changes in morphology and the expression of β-cell-specific marker genes such as PDX1, GLUT2, SST, NKX6.1, PAX4, and NGN3 as analyzed by RT-qPCR. The differentiated cells secreted insulin and C-peptide upon glucose challenge and also they expressed insulin, PDX1, PAX4, NGN3, and GLUT2 at protein level as assessed by immunostaining confirming the successful differentiation to β cell-like cells. Porcine EMSCs possess all the characteristics of MSCs and are suitable model for studying molecular mechanisms of cellular differentiation.

Iberian pig mesenchymal stem/stromal cells from dermal skin, abdominal and subcutaneous adipose tissues, and peripheral blood: in vitro characterization and migratory properties in inflammation

Background

Recently, the capacity of mesenchymal stem/stromal cells (MSCs) to migrate into damaged tissues has been reported. For MSCs to be a promising tool for tissue engineering and cell and gene therapy, it is essential to know their migration ability according to their tissue of origin. However, little is known about the molecular mechanisms regulating porcine MSC chemotaxis. The aim of this study was to examine the migratory properties in an inflammatory environment of porcine MSC lines from different tissue origins: subcutaneous adipose tissue (SCA-MSCs), abdominal adipose tissue (AA-MSCs), dermal skin tissue (DS-MSCs) and peripheral blood (PB-MSCs).

Methods

SCA-MSCs, AA-MSCs, DS-MSCs and PB-MSCs were isolated and analyzed in terms of morphological features, alkaline phosphatase activity, expression of cell surface and intracellular markers of pluripotency, proliferation, in vitro chondrogenic, osteogenic and adipogenic differentiation capacities, as well as their ability to migrate in response to inflammatory cytokines.

Results

SCA-MSCs, AA-MSCs, DS-MSCs and PB-MSCs were isolated and showed plastic adhesion with a fibroblast-like morphology. All MSC lines were positive for CD44, CD105, CD90 and vimentin, characteristic markers of MSCs. The cytokeratin marker was also detected in DS-MSCs. No expression of MHCII or CD34 was detected in any of the four types of MSC. In terms of pluripotency features, all MSC lines expressed POU5F1 and showed alkaline phosphatase activity. SCA-MSCs had a higher growth rate compared to the rest of the cell lines, while the AA-MSC cell line had a longer population doubling time. All MSC lines cultured under adipogenic, chondrogenic and osteogenic conditions showed differentiation capacity to the previously mentioned mesodermal lineages. All MSC lines showed migration ability in an agarose drop assay. DS-MSCs migrated greater distances than the rest of the cell lines both in nonstimulated conditions and in the presence of the inflammatory cytokines TNF-α and IL-1β. SCA-MSCs and DS-MSCs increased their migration capacity in the presence of IL-1β as compared to PBS control.

Conclusions

This study describes the isolation and characterization of porcine cell lines from different tissue origin, with clear MSC properties. We show for the first time a comparative study of the migration capacity induced by inflammatory mediators of porcine MSCs of different tissue origin.

Neurogenic differentiation of adipose derived stem cells on graphene-based mat

Adipose derived stem cells (ADSCs) have been proved as an abundant and accessible cell source with the ability to differentiate into neuron-like cells. However, the low differentiation efficiency puts forward an important challenge to practical applications in clinic. Considering of the good biocompatibility of graphene-based materials and the potential interaction between graphene and cells mentioned in previous studies, herein, we investigated the effect of graphene oxide (GO) and reduced graphene oxide (rGO) mats on neurogenic differentiation of the ADSCs. We demonstrated the excellent capabilities of graphene-based mats, especially GO to support the neural differentiation of ADSCs. By comparing the observation under an optical microscope and fluorescence microscope, the conversion rate of neuron-like cells reached about 90%. We consider that GO mat is better for promoting the differentiation of ADSCs into neuron-like cells, which compared to rGO based platforms. Meanwhile, we made an analysis of the mechanism by which graphene induced the differentiation of ADSCs to neuron-like cells. The data obtained here highlight the effect of GO mat on neurogenic differentiation of ADSCs and implicate the potential of graphene-based materials in application of neural tissue engineering for the limited self-repair capability of nerve cells.

Adult multipotent stromal cell cryopreservation: Pluses and pitfalls

Study and clinical testing of adult multipotent stromal cells (MSCs) are central to progressive improvements in veterinary regenerative medicine. Inherent limitations to long-term culture preclude use for storage. Until cell line creation from primary isolates becomes routine, MSC stasis at cryogenic temperatures is required for this purpose. Many protocols and reagents, including cryoprotectants, used for veterinary MSCs are derived from those for human and rodent cells. Dissimilarities in cryopreservation strategies play a role in variable MSC behaviors. Familiarity with contemporary cryopreservation reagents and processes is essential to an appreciation of their impact on MSC survival and post-cryopreservation behavior. In addition to these points, this review includes a brief history and description of current veterinary stem cell regulation.

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."

Properties of porcine adipose-derived stem cells and their applications in preclinical models

Adipose-derived stem cells represent a reliable adult stem cell source thanks to their abundance, straightforward isolation, and broad differentiation abilities. Consequently, human adipose-derived stem cells (hASCs) have been used in vitro for several innovative cellular therapy and regenerative medicine applications. However, the translation of a novel technology from the laboratory to the clinic requires first to evaluate its safety, feasibility, and potential efficacy through preclinical studies in animals. The anatomy and physiology of pigs and humans are very similar, establishing pigs as an attractive and popular large animal model for preclinical studies. Knowledge of the properties of porcine adipose-derived stem cells (pASCs) used in preclinical studies is critical for their success. While hASCs have been extensively studied this past decade, only a handful of reports relate to pASCs. The aim of this concise review is to summarize the current findings about the isolation of pASCs, their culture, proliferation, and immunophenotype. The differentiation abilities of pASCs and their applications in porcine preclinical models will also be reported.

Tissue-engineered sling with adipose-derived stem cells under static mechanical strain

The implantation of a suburethral sling is an important treatment for stress urinary incontinence (SUI). However, the slings used current have a number of inherent limitations, such as tissue rejection and infection. The present study investigated the potential of engineering sling tissue in vitro using adipose-derived stem cells (ADSCs). The ADSCs were obtained from Sprague-Dawley rats and were characterized in vitro. The ADSCs were seeded on polyglycolic acid (PGA) fibers that formed a scaffold with a shape mimicking a sling complex. The results demonstrated that following in vitro culture for 12 weeks under static strain, neo-sling tissue could be generated using ADSCs. With increasing culture time, the engineered neo-sling tissue exhibited a significant improvement in biomechanical properties, including maximal load and Young's modulus (P<0.05), and the tissue and collagen structures matured. Furthermore, differentiated ADSCs cultured under static strain were maintained their myoblast phenotype within the PGA scaffolds. These results indicate that ADSCs may serve as a novel cell source for tissue sling engineering and could improve treatment for patients with SUI.

Cell viability and extracellular matrix synthesis in a co-culture system of corneal stromal cells and adipose-derived mesenchymal stem cells

AIM

To investigate the impact of adipose-derived mesenchymal stem cells (ADSCs) on cell viability and extracellular matrix (ECM) synthesis of corneal stromal cells (CSCs).

METHODS

ADSCs and CSCs were obtained from the corneas of New Zealand white rabbits and indirectly co-cultured in vitro. The proliferative capacity of CSCs in the different groups was assessed by CCK-8 assays. Annexin V-fluorescein isothiocyanate (FITC)/proliferation indices (PI) assays were used to detect the apoptosis of CSCs. The expression levels of matrix metalloproteinase (MMP), such as MMP1, MMP2, MMP9, and collagens were also evaluated by Western blot.

RESULTS

ADSCs significantly promoted proliferation and invasion of CSCs in the indirect co-culture assays. The co-cultural group displayed much higher ability of proliferation, especially under the co-culture conditions of ADSCs for 3d, compared with that CSCs cultured alone. The PI of CSCs in the co-culture system were increased approximately 3-8-fold compared with the control group. A significant change was observed in the proportions of cells at apoptosis (early and late) between the negative control group (6.34% and 2.06%) and the ADCSs-treated group (4.69% and 1.59%). The expression levels of MMPs were down regulated in the co-culture models. Compared with the control group, the decrease intensities of MMP-1, MMP-2 and MMP-9 in CSCs/ADSCs group were observed, 3.90-fold, 1.09-fold and 3.03-fold, respectively. However, the increase intensities of collagen type (I, II, III, IV, and V) in CSCs were observed in CSCs/ADSCs group, 3.47-fold, 4.30-fold, 2.35-fold, 2.55-fold and 2.43-fold, respectively, compared to that in the control group. The expressions of aldehyde dehydrogenase and fibronectin in CSCs were upregulated in the co-culture models.

CONCLUSION

ADSCs play a promotive role in CSCs' growth and invasion, which may be partially associated with MMPs decrease and collagens increase, resulting in a positive participation in the plasticity and ECM synthesis of CSCs. This provided a new insight into the extensive role of ADSCs in CSCs and a potential molecular target for corneal therapy.

Safety profile and long-term engraftment of human CD31+ blood progenitors in bone tissue engineering

BACKGROUND

Endothelial progenitor cells (EPCs) participate in angiogenesis and induce favorable micro-environments for tissue regeneration. The efficacy of EPCs in regenerative medicine is extensively studied; however, their safety profile remains unknown. Therefore, our aims were to evaluate the safety profile of human peripheral blood-derived EPCs (hEPCs) and to assess the long-term efficacy of hEPCs in bone tissue engineering.

METHODS

hEPCs were isolated from peripheral blood, cultured and characterized. β tricalcium phosphate scaffold (βTCP, control) or 10⁶ hEPCs loaded onto βTCP were transplanted in a nude rat calvaria model. New bone formation and blood vessel density were analyzed using histomorphometry and micro-computed tomography (CT). Safety of hEPCs using karyotype analysis, tumorigenecity and biodistribution to target organs was evaluated.

RESULTS

On the cellular level, hEPCs retained their karyotype during cell expansion (seven passages). Five months following local hEPC transplantation, on the tissue and organ level, no inflammatory reaction or dysplastic change was evident at the transplanted site or in distant organs. Direct engraftment was evident as CD31 human antigens were detected lining vessel walls in the transplanted site. In distant organs human antigens were absent, negating biodistribution. Bone area fraction and bone height were doubled by hEPC transplantation without affecting mineral density and bone architecture. Additionally, local transplantation of hEPCs increased blood vessel density by nine-fold.

CONCLUSIONS

Local transplantation of hEPCs showed a positive safety profile. Furthermore, enhanced angiogenesis and osteogenesis without mineral density change was found. These results bring us one step closer to first-in-human trials using hEPCs for bone regeneration.

Incorporation of well-dispersed calcium phosphate nanoparticles into PLGA electrospun nanofibers to enhance the osteogenic induction potential

PAA modified Zn-doped HAp-like calcium phosphate (PAA-CaP/Zn) nanoparticles were homogeneously distributed in PLGA electrospun nanofibers, and enhanced the osteogenic differentiation of rADSCs.

Histological and Urodynamic Effects of Autologous Stromal Vascular Fraction Extracted from Fat Tissue with Minimal Ex Vivo Manipulation in a Porcine Model of Intrinsic Sphincter Deficiency

PURPOSE

To evaluate the healing abilities of autologous stem cell therapy (stromal vascular fraction) prepared from adipose tissue we used an automated system without an ex vivo culture phase in a pig model of intrinsic sphincteric deficiency.

MATERIALS AND METHODS

A total of 15 pigs underwent endoscopic section of the urethral sphincter. Animals were then randomly assigned to 3 groups, including 1) controls without stromal vascular fraction injection, 2) early injection with stromal vascular fraction 2 to 3 days after section and 3) late stromal vascular fraction injection delivery 30 days after injury. Extraction and stromal vascular fraction injection were performed as a single procedure. The stromal vascular fraction was characterized by flow cytometry. Mesenchymal stem cell-like cells were enumerated by clonogenicity (cfu fibroblast) assay. Study end points included histological assessment of the urethral injury surface and urodynamics to determine maximum urethral pressure.

RESULTS

Flow cytometry analysis revealed a mesenchymal stem cell-like phenotype in a mean ± SD of 47.3% ± 11.8% of stromal vascular fraction cells. The cfu fibroblast frequency was 1.3 to 6.6/100 stromal vascular fraction cells (1.3% to 6.6%). Stromal vascular fraction injection was associated with a reduction of the urethral injury surface in the early and late injection groups compared with the respective controls (7% vs 17% and 1% vs 13%, p = 0.050 and 0.029, respectively). On day 30 after injection maximum urethral pressure was significantly higher in the injected groups than in the control group, that is 64% vs 50% of maximum urethral pressure on day 0 (p = 0.04).

CONCLUSIONS

These data demonstrate the ability of an autologous stromal vascular fraction to improve the urethral healing process in a large animal model of intrinsic sphincteric deficiency.

Investigation of synergistic effects of inductive and conductive factors in gelatin-based cryogels for bone tissue engineering

Macroporous and biocompatible scaffolds for bone tissue engineering were prepared from 4% gelatin (G) and 4% gelatin/2% nanohydroxyapatite (nHAP), (GN), by cryogelation. The cryogels have interconnected pores with pore size around 100 μm and a high degree of cross-linking. The incorporation of nHAP slightly reduced the porosity, degree of crosslinking, swelling kinetics and equilibrium water uptake, but enhanced the toughness of the cryogel scaffolds. The osteo-regeneration potential of GN cryogels was further enhanced by binding with bone morphogenetic protein (BMP-2) to produce the gelatin/nHAP/BMP-2 (GNB) scaffold. The efficacy of BMP-2 incorporation was tested through in vitro release studies and a sustained release profile could be observed from the cumulative BMP-2 release curve. To elucidate the effect of cryogel composition on cell proliferation and differentiation, rabbit adipose-derived stem cells (ADSCs) were seeded in cryogel scaffolds. In vitro studies demonstrated a reduced proliferation rate and enhanced osteogenic differentiation of ADSCs in GNB cryogel scaffolds from the combined effect of nHAP and BMP-2, judging from the elevated alkaline phosphatase activity and the degree of mineralization. Confocal microscopy confirmed high viability and good cytoskeletal spreading of ADSCs on cryogels while osteocalcin (OCN) protein quantification affirmed the dominance of GNB in the osteogenic differentiation of ADSCs compared to G and GN cryogels. The maximum osteogenesis capability of GNB was also confirmed through the up-regulation of specific bone maker genes of early marker protein collagen I (COL I) and late marker protein osteopontin (OPN). From an in vivo animal model, computed tomography analysis confirmed the superior bone regeneration capability of ADSCs in GNB cryogels by implanting ADSCs/GNB cryogel constructs in rabbit calvarial critical size defects. Histological and immunohistochemical analysis demonstrated new bone formation and continued expression of COL I and OCN bone-specific proteins at the defect site. Taken together, the results demonstrate that G cryogels modified with osteo-conductive nHAP and osteo-inductive BMP-2 could provide cues to synergistically promote the osteogenesis of ADSCs in vitro and in vivo.

INVITED REVIEW: Evolution of meat animal growth research during the past 50 years: Adipose and muscle stem cells

If one were to compare today's animal growth research to research from a mere 50 yr ago, one would see programs with few similarities. The evolution of this research from whole-animal through cell-based and finally molecular and genomic studies has been enhanced by the identification, isolation, and in vitro evaluation of adipose- and muscle-derived stem cells. This paper will highlight the struggles and the milestones that make this evolving area of research what it is today. The contribution of adipose and muscle stem cell research to development and growth, tissue regeneration, and final carcass composition are reviewed.

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.

Sox9-Positive Progenitor Cells Play a Key Role in Renal Tubule Epithelial Regeneration in Mice

The kidney has a tremendous capacity to regenerate following injury, but factors that govern this response are still largely unknown. We isolated cells from mouse kidneys with high proliferative and multi-lineage differentiation capacity. These cells expressed a high level of Sox9. In regenerating kidneys, Sox9 expression was induced early, and 89% of proliferating cells were Sox9 positive. In vitro, Sox9-positive cells showed unlimited proliferation and multi-lineage differentiation capacity. Using an inducible Sox9 Cre line and lineage-tagging methods, we show that Sox9-positive cells can generate new daughter cells, contributing to the regeneration of proximal tubule, loop of Henle, and distal tubule segments but not to collecting duct and glomerular cells. Furthermore, inducible deletion of Sox9 resulted in reduced epithelial proliferation, more severe injury, and fibrosis development. In summary, we demonstrate that, in the kidney, Sox9-positive cells show progenitor-like properties in vitro and contribute to epithelial regeneration following injury in vivo.

Adipose-derived stem cells seeded on polyglycolic acid for the treatment of stress urinary incontinence

PURPOSE

To evaluate the effect and possible mechanism of suburethral tissue-engineered sling in an animal model of stress urinary incontinence (SUI).

METHODS

Adipose-derived stem cells (ADSCs) were obtained from the adipose tissues of rats. The differentiation potential, proliferation, and viability of rat ADSCs were evaluated after infecting these cells with a lentiviral vector-encoding green fluorescent protein (GFP). Next, GFP transfected ADSCs were seeded on polyglycolic acid (PGA) fibers to construct the tissue-engineered sling with the induction of 5-azacytidine (5-Aza). Afterward, the tissue-engineered slings were transplanted into a rat model of SUI that was established by vaginal balloon dilatation method and bilateral ovariectomy. Histology and the leak point pressure measurements were performed at 2 months after tissue-engineered sling implantation.

RESULTS

The ADSCs were found to be efficiently transfected with GFP, without any effects on proliferation, cell cycle and multi-differentiation potential. After been seeded on PGA fibers, ADSCs formed tissue-engineered slings in 4 weeks of induction culture. Two months after implantation, the mean leak point pressure (LPP) was significantly increased in sling-treated rats compared with the balloon-injured ovariectomized rats. Immunofluorescence assay showed that some of the GFP expressing cells stained positive for muscle-specific markers.

CONCLUSIONS

The newly suburethral tissue-engineered sling restores LPP in the rat model of SUI, which could be an effective treatment in future SUI therapy.

Fat harvesting site is an important determinant of proliferation and pluripotency of adipose-derived stem cells

To define the optimal fat harvest site and detect any potential differences in adipose-derived stem cells (ASCs) proliferation properties in camels, aspirates from the abdomen and hump sites were compared. Obtained results revealed that ASCs from both abdomen and hump exhibited spindle-shaped and fibroblast-like morphology with hump-derived ASCs being smaller in size and narrower in overall appearance than abdominal ASCs. Abdominal ASCs required a greater time for proliferation than the hump-derived cells. These results were further confirmed with a tetrazolium-based colorimetric assay (MTT) which showed a greater cell proliferation rate for hump ASCs than for the abdomen. Under inductive conditions, ASCs from both abdominal and hump fat deposits maintained their lineage differentiation potential into adipogenic, chondrogenic, and osteogenic lineages during subsequent passages without any qualitative difference. However, expression of alkaline phosphatase was higher in osteogenic differentiated cells from the hump compared with those of the abdomen. Moreover, the increase in calcium content in hump-derived stem cells was higher than that in abdominal-derived stem cells. In conclusion, our findings revealed that ASCs can be obtained from different anatomical locations, although ASCs from the hump fat region may be the ideal stem cell sources for use in cell-based therapies.

Modulation of keratin in adhesion, proliferation, adipogenic, and osteogenic differentiation of porcine adipose-derived stem cells

Recently, keratin attracts tremendous interest because of its intrinsic ability to interact with different cells. It has the potential to serve as a controllable extracellular matrix protein that can be used to demonstrate cell mechanism and cell-matrix interaction. However, there have been relatively few studies on the effects of keratin on stem cells. In the present work, we study the effects of human keratin on porcine adipose-derived stem cells (pASCs) and a series of selective cell lines: 3T3 fibroblasts, Madin-Darby canine kidney (MDCK) cells, and MG63 osteoblasts. Relative to un-treated culture plate, our results showed that keratin coating substrates promote cell adhesion and proliferation to above cell lines. Keratin also improved pASCs adhesion, proliferation, and enhanced cell viability. Evaluation of genetic markers showed that adipogenic and osteogenic differentiations of pASCs can be successfully induced, thus demonstrating that keratin did not influence the stemness of pASCs. Furthermore, keratin improved adipogenic differentiations of pASCs in terms of up-regulations in lipoprotein lipase, peroxisome proliferator-activated receptor gamma, and CCAAT-enhancer-binding protein alpha. The osteogenic markers type I collagen, runt-related transcription factor 2, and vitamin D receptor were also upregulated when pASCs cultured on keratin substrates. Therefore, keratin can serve as a biological derived material for surface modification and scaffold fabrication for biomedical purpose. The combination of keratin with stem cells may be a potential candidate for tissue repair in the field of regenerative medicine. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 180-192, 2017.

Therapeutic doses of multipotent stromal cells from minimal adipose tissue

Low yield of adult adipose-derived multipotent stromal cells (ASC) can limit autologous cell therapy in individuals with minimal adipose tissue. In this study, ASC isolation was optimized from approximately 0.2 g of feline epididymal adipose tissue for a treatment dose of 10⁶–10⁷ ASCs/kg. The ASC yield was determined for three digestions, 0.1 % collagenase in medium for 30 min (Classic), 0.3 % collagenase in buffer for 30 min (New) and 0.3 % collagenase in buffer for 1 h (Hour). After isolation by the new tissue digestion, continuously cultured ASCs (fresh) and cells recovered and expanded after cryostorage at P0 (revitalized) were characterized up to cell passage (P) 5. Outcomes included CD9, CD29, CD44, CD90 and CD105 expression, cell doublings and doubling times, fibroblastic, adipogenic and osteogenic colony forming unit (CFU) frequency percentages and lineage-specific target gene expression after induction. The New digestion had the highest CFU yield, and about 7x10⁶ ASCs/kg were available within three cell passages (P2). Compared to earlier passages, target surface antigen expression was lowest in fresh P5 cells, and fresh and revitalized P3–5 cells had slower expansion. Fresh and revitalized P1 ASCs had higher CFU frequency percentages and lineage-specific gene expression than P3. The New method described in this study was most efficient for feline epididymal ASC isolation and did not alter in vitro cell behavior. Fresh and revitalized P0-P2 feline ASCs may be most effective for preclinical and clinical trials. This study offers a potential option for ASC isolation from limited adipose tissue resources across species.

The stem cell potential and multipotency of human adipose tissue-derived stem cells vary by cell donor and are different from those of other types of stem cells

Human adipose tissue-derived mesenchymal stem cells (AT-MSCs) from various sites are applied in tissue engineering and cell therapy. The condition of AT-MSCs depends on the donor's age, body mass index (BMI), and gender. AT-MSCs from 66 human donors were analyzed, and the cells were sorted according to donor age (10-19 years: n = 1; 20-29 years: n = 5; 30-39 years: n = 12; 40-49 years: n = 22; 50-59 years: n = 12; 60-69 years: n = 9, and 70 years or older: n = 5), BMI (under 25, 25-30, and over 30), and gender (19 males and 48 females). Additionally, AT-MSCs were compared to bone marrow MSCs and chorionic tissue-derived MSCs. We measured the MSC yield, growth rate, colony-forming units, multipotency, and surface antigens. AT-MSC proliferation was greater in cells isolated from individuals aged less than 30 years compared to the proliferation of AT-MSCs from those over 50 years old. BMI was correlated with osteogenic differentiation potency; increased BMI enhanced osteogenesis. Adipogenic differentiation was more strongly induced in cells isolated from donors aged less than 30 years compared to those isolated from other age groups. Also, a BMI above 30 was associated with enhanced adipogenic differentiation compared to cells isolated from individuals with a BMI below 25. Bone marrow MSCs were strongly induced to differentiate along both osteogenic and adipogenic lineages, whereas AT-MSCs predominantly differentiated into the chondrogenic lineage. Therefore, the type of regeneration required and variations among potential donors must be carefully considered when selecting MSCs for use in applied tissue engineering or cell therapy.

Induction of Osteogenic Differentiation in Human Mesenchymal Stem Cells by Crosstalk with Osteoblasts

Natural bone healing following fractures is initiated by osteoblasts (OBs) and mesenchymal stem cells (MSCs), a cell combination with possible potential in tissue engineering techniques for bony defects. The aim of the study was to investigate MSC/OB-crosstalk, in order to determine optimal cell culture conditions for osteogenic differentiation. Human OBs and MSCs interactions were investigated in an in vitro trans-well co-culture study over a time period of 28 days. Calcification was determined by optical density (OD) at 450 nm and Alizarin red staining. Messenger RNA expression was assessed by quantitative PCR. Osteogenic medium containing 1% fetal bovine serum resulted in superior levels of calcification in MSCs in co-culture with OBs compared to 2% or 5% fetal bovine serum (p<0.05). Comparing MSCs and OBs alone with the MSC/OB co-culture, calcification, as measured by OD 450 nm, increased over time in all groups. The highest values were recorded in the co-culture (p<0.05). Osteogenic differentiation potential showed significant interindividual differences. In order to predict differentiation potential, OD 450 nm measurements and mRNA expression of alkaline phosphatase were correlated with the population doubling rate during the expansion period. For OBs and MSCs, statistically significant associations of proliferation and differentiation potential were found (p<0.001). The addition of transforming growth factor beta resulted in up-regulation of collagen type I and Sp7 mRNA, and down-regulation of alkaline phosphatase mRNA. The results suggest the idea of soluble paracrine factors being secreted by OBs to induce osteogenic differentiation of MSCs.

Periodontal tissue regeneration by transplantation of rat adipose-derived stromal cells in combination with PLGA-based solid scaffolds

Regeneration of damaged periodontium is challenging due to its multi-tissue composition. Mesenchymalstem cell-based approaches using adipose-derived stromal cells (ASCs) may contribute to periodontal reconstruction, particularly when combined with the use of scaffolds to maintain a space for new tissue growth. The aim of this study was to assess the regenerative potential of ASCs derived from inbred or outbred rats in combination with novel solid scaffolds composed of PLGA (Poly D,L-lactic-co-glycolic acid) (PLGA-scaffolds). Cultured ASCs seeded onto PLGA scaffolds (ASCs/PLGA) or PLGA-scaffolds (PLGA) alone were transplanted into periodontal fenestration defects created in F344 or Sprague Dawley (SD) rats. Micro-CT analysis showed a significantly higher percentage of bone growth in the ASCs/PLGA groups compared with the PLGA-alone groups at five weeks after surgery. Similarly, histomorphometric analysis demonstrated thicker growth of periodontal ligament and cementum layers in the ASCs/PLGA-groups compared with the PLGA-alone groups. In addition, transplanted DiI-labeled ASCs were observed in the periodontal regenerative sites. The present investigation demonstrated the marked ability of ASCs in combination with PLGA scaffolds to repair periodontal defects.