Enhanced Chondrogenic Differentiation Potential of Human Gingival Fibroblasts by Spheroid Formation on Chitosan Membranes

Enhancement of Chondrogenic Differentiation in Bone Marrow-Derived Stem Cell Spheroids by Cuminum cyminum Methanolic Extract: Insights into Concentration-Dependent mRNA Expression and Gene Clustering Analysis

Background/Objectives: Cuminum cyminum L. has been utilized as a medicinal plant for centuries. This research sought to examine the effects of cumin methanolic extract (CMT) on the chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells. Methods: Spheroids were generated using human stem cells and cultured with CMT at concentrations between 0 and 1 µg/mL. Morphological assessments and cell viability tests were conducted on days 1 and 3. Chondrogenic differentiation expression was evaluated through quantitative polymerase chain reaction, Western blot, and RNA sequencing. SOX9, FAM20B, COL2A1, and COL1A1 mRNA expression levels were determined using real-time polymerase chain reaction. Protein expression was analyzed via Western blot. Results: Throughout this study, the spheroids maintained their integrity and shape. No significant variations in spheroid diameter were observed among the groups. CMT treatment enhanced the expression of SOX9 and FAM20B. Conclusions: The methanolic extract of Cuminum cyminum facilitated chondrogenic differentiation in human bone marrow-derived mesenchymal stem cells by modulating SOX9 and FAM20B expression. This indicates its potential application in cartilage tissue engineering.

Hiding in Plain Sight: Human Gingival Fibroblasts as an Essential, Yet Overlooked, Tool in Regenerative Medicine

Adult human gingival fibroblasts (HGFs), the most abundant cells in the oral cavity, are essential for maintaining oral homeostasis. Compared with other tissues, adult oral mucosal wounds heal regeneratively, without scarring. Relative to fibroblasts from other locations, HGFs are relatively refractory to myofibroblast differentiation, immunomodulatory, highly regenerative, readily obtained via minimally invasive procedures, easily and rapidly expanded in vitro, and highly responsive to growth factors and cytokines. Consequently, HGFs might be a superior, yet perhaps underappreciated, source of adult mesenchymal progenitor cells to use in tissue engineering and regeneration applications, including the treatment of fibrotic auto-immune connective tissue diseases such as scleroderma. Herein, we highlight in vitro and translational studies that have investigated the regenerative and differentiation potential of HGFs, with the objective of outlining current limitations and inspiring future research that could facilitate translating the regenerative potential of HGFs into the clinic.

Graphene Oxide-Coated Patterned Silk Fibroin Films Promote Cell Adhesion and Induce Cardiomyogenic Differentiation of Human Mesenchymal Stem Cells

Cardiac tissue engineering is a promising strategy for the treatment of myocardial damage. Mesenchymal stem cells (MSCs) are extensively used in tissue engineering. However, transformation of MSCs into cardiac myocytes is still a challenge. Furthermore, weak adhesion of MSCs to substrates often results in poor cell viability. Here, we designed a composite matrix based on silk fibroin (SF) and graphene oxide (GO) for improving the cell adhesion and directing the differentiation of MSCs into cardiac myocytes. Specifically, patterned SF films were first produced by soft lithographic. After being treated by air plasma, GO nanosheets could be successfully coated on the patterned SF films to construct the desired matrix (P-GSF). The resultant P-GSF films presented a nano-topographic surface characterized by linear grooves interlaced with GO ridges. The P-GSF films exhibited high protein absorption and suitable mechanical strength. Furthermore, the P-GSF films accelerated the early cell adhesion and directed the growth orientation of MSCs. RT-PCR results and immunofluorescence imaging demonstrated that the P-GSF films significantly improved the cardiomyogenic differentiation of MSCs. This work indicates that patterned SF films coated with GO are promising matrix in the field of myocardial repair tissue engineering.

Botanicals and Oral Stem Cell Mediated Regeneration: A Paradigm Shift from Artificial to Biological Replacement

Stem cells are a well-known autologous pluripotent cell source, having excellent potential to develop into specialized cells, such as brain, skin, and bone marrow cells. The oral cavity is reported to be a rich source of multiple types of oral stem cells, including the dental pulp, mucosal soft tissues, periodontal ligament, and apical papilla. Oral stem cells were useful for both the regeneration of soft tissue components in the dental pulp and mineralized structure regeneration, such as bone or dentin, and can be a viable substitute for traditionally used bone marrow stem cells. In recent years, several studies have reported that plant extracts or compounds promoted the proliferation, differentiation, and survival of different oral stem cells. This review is carried out by following the PRISMA guidelines and focusing mainly on the effects of bioactive compounds on oral stem cell-mediated dental, bone, and neural regeneration. It is observed that in recent years studies were mainly focused on the utilization of oral stem cell-mediated regeneration of bone or dental mesenchymal cells, however, the utility of bioactive compounds on oral stem cell-mediated regeneration requires additional assessment beyond in vitro and in vivo studies, and requires more randomized clinical trials and case studies.

Chondrogenic Potential of Dental-Derived Mesenchymal Stromal Cells

The field of tissue engineering has revolutionized the world in organ and tissue regeneration. With the robust research among regenerative medicine experts and researchers, the plausibility of regenerating cartilage has come into the limelight. For cartilage tissue engineering, orthopedic surgeons and orthobiologists use the mesenchymal stromal cells (MSCs) of various origins along with the cytokines, growth factors, and scaffolds. The least utilized MSCs are of dental origin, which are the richest sources of stromal and progenitor cells. There is a paradigm shift towards the utilization of dental source MSCs in chondrogenesis and cartilage regeneration. Dental-derived MSCs possess similar phenotypes and genotypes like other sources of MSCs along with specific markers such as dentin matrix acidic phosphoprotein (DMP) -1, dentin sialophosphoprotein (DSPP), alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and STRO-1. Concerning chondrogenicity, there is literature with marginal use of dental-derived MSCs. Various studies provide evidence for in-vitro and in-vivo chondrogenesis by dental-derived MSCs. With such evidence, clinical trials must be taken up to support or refute the evidence for regenerating cartilage tissues by dental-derived MSCs. This article highlights the significance of dental-derived MSCs for cartilage tissue regeneration.

Gingiva-Derived Mesenchymal Stem Cells: Potential Application in Tissue Engineering and Regenerative Medicine - A Comprehensive Review

A unique subpopulation of mesenchymal stem cells (MSCs) has been isolated and characterized from human gingival tissues (GMSCs). Similar to MSCs derived from other sources of tissues, e.g. bone marrow, adipose or umbilical cord, GMSCs also possess multipotent differentiation capacities and potent immunomodulatory effects on both innate and adaptive immune cells through the secretion of various types of bioactive factors with immunosuppressive and anti-inflammatory functions. Uniquely, GMSCs are highly proliferative and have the propensity to differentiate into neural cell lineages due to the neural crest-origin. These properties have endowed GMSCs with potent regenerative and therapeutic potentials in various preclinical models of human disorders, particularly, some inflammatory and autoimmune diseases, skin diseases, oral and maxillofacial disorders, and peripheral nerve injuries. All types of cells release extracellular vesicles (EVs), including exosomes, that play critical roles in cell-cell communication through their cargos containing a variety of bioactive molecules, such as proteins, nucleic acids, and lipids. Like EVs released by other sources of MSCs, GMSC-derived EVs have been shown to possess similar biological functions and therapeutic effects on several preclinical diseases models as GMSCs, thus representing a promising cell-free platform for regenerative therapy. Taken together, due to the easily accessibility and less morbidity of harvesting gingival tissues as well as the potent immunomodulatory and anti-inflammatory functions, GMSCs represent a unique source of MSCs of a neural crest-origin for potential application in tissue engineering and regenerative therapy.

Recent Advances in Three-Dimensional Multicellular Spheroid Culture and Future Development

Three-dimensional multicellular spheroids (MCSs) have received extensive attention in the field of biomedicine due to their ability to simulate the structure and function of tissues in vivo more accurately than traditional in vitro two-dimensional models and to simulate cell-cell and cell extracellular matrix (ECM) interactions. It has become an important in vitro three-dimensional model for tumor research, high-throughput drug screening, tissue engineering, and basic biology research. In the review, we first summarize methods for MCSs generation and their respective advantages and disadvantages and highlight the advances of hydrogel and microfluidic systems in the generation of spheroids. Then, we look at the application of MCSs in cancer research and other aspects. Finally, we discuss the development direction and prospects of MCSs.

Engineering Multi-Cellular Spheroids for Tissue Engineering and Regenerative Medicine

Multi-cellular spheroids are formed as a 3D structure with dense cell-cell/cell-extracellular matrix interactions, and thus, have been widely utilized as implantable therapeutics and various ex vivo tissue models in tissue engineering. In principle, spheroid culture methods maximize cell-cell cohesion and induce spontaneous cellular assembly while minimizing cellular interactions with substrates by using physical forces such as gravitational or centrifugal forces, protein-repellant biomaterials, and micro-structured surfaces. In addition, biofunctional materials including magnetic nanoparticles, polymer microspheres, and nanofiber particles are combined with cells to harvest composite spheroids, to accelerate spheroid formation, to increase the mechanical properties and viability of spheroids, and to direct differentiation of stem cells into desirable cell types. Biocompatible hydrogels are developed to produce microgels for the fabrication of size-controlled spheroids with high efficiency. Recently, spheroids have been further engineered to fabricate structurally and functionally reliable in vitro artificial 3D tissues of the desired shape with enhanced specific biological functions. This paper reviews the overall characteristics of spheroids and general/advanced spheroid culture techniques. Significant roles of functional biomaterials in advanced spheroid engineering with emphasis on the use of spheroids in the reconstruction of artificial 3D tissue for tissue engineering are also thoroughly discussed.

The response of gingiva monolayer, spheroid, and ex vivo tissue cultures to collagen membranes and bone substitute

Collagen membranes and bone substitute are popular biomaterials in guided tissue regeneration for treatment of traumatized or diseased periodontal tissue. Development of these biomaterials starts in monolayer cell culture, failing to reflect in vivo tissue organization. Spheroid cultures potentially mimic in vivo tissues in structure and functionality. This study aims to compare gingiva cell (GC) monolayers and spheroids to ex vivo gingiva. Human GC monolayers, spheroids and gingiva ex vivo tissues were cultured on plastic surfaces, collagen membranes or bone substitute. Hematoxylin-eosin (HE) staining, immunohistochemistry for KI67 and caspase 3 (CASP3), resazurin-based toxicity assays, quantitative polymerase chain reaction for collagen I (COL1A1), vascular endothelial growth factor (VEGF), angiogenin (ANG), interleukin (IL)6 and IL8 and ELISA for COL1A1, VEGF, ANG, IL6 and IL8 were performed in all cultures. Morphology was different in all culture set-ups. Staining of KI67 was positive in monolayers and staining of CASP3 was positive in spheroids. All culture set-ups were viable. COL1A1 production was modulated in monolayers and ex vivo tissues at mRNA levels, VEGF in monolayers and ex vivo tissues at mRNA levels and in spheroids at protein levels, ANG in spheroids at mRNA levels and in monolayers and spheroids at protein levels, IL6 in monolayers and spheroids at mRNA levels and in spheroids and ex vivo tissues at protein levels and IL8 in monolayers and ex vivo tissues at mRNA levels. Modulations were surface-dependent. In conclusion, each culture model is structurally and functionally different. Neither GC monolayers nor spheroids mimicked gingiva ex vivo tissue in all measured aspects.

Head to Knee: Cranial Neural Crest-Derived Cells as Promising Candidates for Human Cartilage Repair

A large array of therapeutic procedures is available to treat cartilage disorders caused by trauma or inflammatory disease. Most are invasive and may result in treatment failure or development of osteoarthritis due to extensive cartilage damage from repeated surgery. Despite encouraging results of early cell therapy trials that used chondrocytes collected during arthroscopic surgery, these approaches have serious disadvantages, including morbidity associated with cell harvesting and low predictive clinical outcomes. To overcome these limitations, adult stem cells derived from bone marrow and subsequently from other tissues are now considered as preferred sources of cells for cartilage regeneration. Moreover, with new evidence showing that the choice of cell source is one of the most important factors for successful cell therapy, there is growing interest in neural crest-derived cells in both the research and clinical communities. Neural crest-derived cells such as nasal chondrocytes and oral stem cells that exhibit chondrocyte-like properties seem particularly promising in cartilage repair. Here, we review the types of cells currently available for cartilage cell therapy, including articular chondrocytes and various mesenchymal stem cells, and then highlight recent developments in the use of neural crest-derived chondrocytes and oral stem cells for repair of cartilage lesions.

Aggregation of human dental pulp cells into 3D spheroids enhances their migration ability after reseeding

Multicellular three-dimensional (3D) spheroids allow intimate cell-cell communication and cell-extracellular matrix interaction. Thus, 3D cell spheroids better mimic microenvironment in vivo than two-dimensional (2D) monolayer cultures. The purpose of this study was to evaluate the behaviors of human dental pulp cells (DPCs) cultured on chitosan and polyvinyl alcohol (PVA) membranes. The protein expression of hypoxia-inducible factor 1-α (HIF-1α) and vascular endothelial growth factor (VEGF), and the migration ability of the DPCs from 2D versus 3D environments were investigated. The results showed that both chitosan and PVA membranes support DPCs aggregation to form multicellular spheroids. In comparison to 2D cultures on tissue culture polystyrene, DPC spheroids exhibited higher protein expression of HIF-1α and VEGF. The treatment with YC-1 (inhibitor to HIF-1α) blocked the upregulation of VEGF, indicating a downstream event to HIF-1α expression. When DPC spheroids were collected and subjected to the transwell assay, the cells growing outward from 3D spheroids showed greater migration ability than those from 2D cultures. Moreover, DPCs aggregation and spheroid formation on chitosan membrane were abolished by Y-27632 (inhibitor to Rho-associated kinases), whereas the inhibitory effect did not exist on PVA membrane. This suggests that the mechanism regulating DPCs aggregation and spheroid formation on chitosan membrane is involved with the Rho-associated kinase signaling pathway. In summary, the multicellular spheroid structure was beneficial to the protein expression of HIF-1α and VEGF in DPCs and enhanced the migration ability of the cells climbing from spheroids. This study showed a new perspective in exploring novel strategies for DPC-based research and application.

Engineering principles for guiding spheroid function in the regeneration of bone, cartilage, and skin

There is a critical need for strategies that effectively enhance cell viability and post-implantation performance in order to advance cell-based therapies. Spheroids, which are dense cellular aggregates, overcome many current limitations with transplanting individual cells. Compared to individual cells, the aggregation of cells into spheroids results in increased cell viability, together with enhanced proangiogenic, anti-inflammatory, and tissue-forming potential. Furthermore, the transplantation of cells using engineered materials enables localized delivery to the target site while providing an opportunity to guide cell fate in situ, resulting in improved therapeutic outcomes compared to systemic or localized injection. Despite promising early results achieved by freely injecting spheroids into damaged tissues, growing evidence demonstrates the advantages of entrapping spheroids within a biomaterial prior to implantation. This review will highlight the basic characteristics and qualities of spheroids, describe the underlying principles for how biomaterials influence spheroid behavior, with an emphasis on hydrogels, and provide examples of synergistic approaches using spheroids and biomaterials for tissue engineering applications.

Neural Crest Stem-Like Cells Non-genetically Induced from Human Gingiva-Derived Mesenchymal Stem Cells Promote Facial Nerve Regeneration in Rats

Non-genetic induction of somatic cells into neural crest stem-like cells (NCSCs) is promising for potential cell-based therapies for post-traumatic peripheral nerve regeneration. Here, we report that human gingiva-derived mesenchymal stem cells (GMSCs) could be reproducibly and readily induced into NCSCs via non-genetic approaches. Compared to parental GMSCs, induced NCSC population had increased expression in NCSC-related genes and displayed robust differentiation into neuronal and Schwann-like cells. Knockdown of the expression of Yes-associated protein 1 (YAP1), a critical mechanosensor and mechanotransducer, attenuated the expression of NCSC-related genes; specific blocking of RhoA/ROCK activity and non-muscle myosin II (NM II)-dependent contraction suppressed YAP1 and NCSC-related genes and concurrently abolished neural spheroid formation in NCSCs. Using a rat model of facial nerve defect, implantation of NCSC-laden nerve conduits promoted functional regeneration of the injured nerve. These promising findings demonstrate that induced NCSCs derived from GMSCs represent an easily accessible and promising source of neural stem-like cells for peripheral nerve regeneration.

Recent advances in 3D bioprinting for the regeneration of functional cartilage

The field of regeneration for functional cartilage has progressed tremendously. Conventional approaches for regenerating the damaged tissue based on integrated manufacturing are limited by their inability to produce precise and customized biomimetic tissues. On the other hand, 3D bioprinting is a promising technique with increased versatility because it can co-deliver cells and biomaterials with proper compositions and spatial distributions. In the present article, we review recent progress in the complete 3D printing process involved in functional cartilage regeneration, including printing techniques, biomaterials and cells. We also discuss the combination of 3D in vivo hybrid bioprinting with spheroids, gene delivery strategies and zonal cartilage design as a future direction of cartilage regeneration research.

Evaluation of the maintenance of stemness, viability, and differentiation potential of gingiva-derived stem-cell spheroids

Gingiva-derived stem cells have been applied for tissue-engineering purposes and may be considered a favorable source of mesenchymal stem cells as harvesting stem cells from the mandible or maxilla may be performed with ease under local anesthesia. The present study was performed to fabricate stem-cell spheroids using concave microwells and to evaluate the maintenance of stemness, viability, and differentiation potential. Gingiva-derived stem cells were isolated, and the stem cells of 4×105 (group A) or 8×105 (group B) cells were seeded into polydimethylsiloxane-based, concave micromolds with 600 µm diameters. The morphology of the microspheres and the change of the diameters of the spheroids were evaluated. The viability of spheroids was qualitatively analyzed via Live/Dead kit assay. A cell viability analysis was performed on days 1, 3, 6, and 12 with Cell Counting Kit-8. The maintenance of stemness was evaluated with immunocytochemical staining using SSEA-4, TRA-1-60(R) (positive markers), and SSEA-1 (negative marker). Osteogenic, adipogenic, and chondrogenic differentiation potential was evaluated by incubating spheroids in osteogenic, adipogenic and chondrogenic induction medium, respectively. The gingiva-derived stem cells formed spheroids in the concave microwells. The diameters of the spheroids were larger in group A than in group B. The majority of cells in the spheroids emitted green fluorescence, indicating the presence of live cells at day 6. At day 12, the majority of cells in the spheroids emitted green fluorescence, and a small portion of red fluorescence was also noted, which indicated the presence of dead cells. The spheroids were positive for the stem-cell markers SSEA-4 and TRA-1-60(R) and were negative for SSEA-1, suggesting that these spheroids primarily contained undifferentiated human stem cells. Osteogenic, adipogenic, and chondrogenic differentiation was more evident with an increase of incubation time: Mineralized extracellular deposits were observed following Alizarin Red S staining at days 14 and 21; oil globules were increased at day 18 when compared with day 6; and Alcian blue staining was more evident at day 18 when compared with day 6. Within the limits of this study, stem-cell spheroids from gingival cells maintained the stemness, viability, and differentiation potential during the experimental periods. This method may be applied for a promising strategy for stem-cell therapy.

Life is 3D: Boosting Spheroid Function for Tissue Engineering

Spheroids provide a 3D environment with intensive cell-cell contacts. As a result of their excellent regenerative properties and rapid progress in their high-throughput production, spheroids are increasingly suggested as building blocks for tissue engineering. In this review, we focus on innovative biotechnological approaches that increase the quality of spheroids for this specific type of application. These include in particular the fabrication of coculture spheroids, mimicking the complex morphology and physiological tasks of natural tissues. In vitro preconditioning under different culture conditions and incorporation of biomaterials improve the function of spheroids and their directed fusion into macrotissues of desired shapes. The continuous development of these sophisticated approaches may markedly contribute to a broad implementation of spheroid-based tissue engineering in future regenerative medicine.

The effect of elastic biodegradable polyurethane electrospun nanofibers on the differentiation of mesenchymal stem cells

Biodegradable polyurethane (PU) was synthesized based on using poly(ɛ-caprolactone) (PCL) as the soft segment. Fibers in different diameters (200-400nm, 600-800nm, and 1.4-1.6μm) were then made by electrospinning PU solution in N,N-dimethylacetamide and 2,2,2-trifluoroethanol. Human bone marrow derived mesenchymal stem cells (hMSCs) in the form of single dispersed cells or aggregates were seeded on the electrospun meshes for evaluation of cell behavior. Differentiation experiments showed that hMSC aggregates on electrospun fibers had greater differentiation capacities than single cells. Besides, nanofibers of 200-400nm diameters significantly promoted the osteogenic and chondrogenic differentiation of hMSCs than fibers of the other diameters. The effect of substrate elasticity was further elucidated by comparing cell behaviors on the nanofibers of PCL-based PU and those of pure PCL. The more elastic PU nanofibers demonstrated more osteogenic and chondrogenic induction potential than PCL electrospun fibers. We suggested that the elastic nanofibers seeded with hMSC aggregates may be advantageous for cartilage and bone tissue engineering.

Enhanced chondrogenic differentiation of dental pulp stem cells using nanopatterned PEG-GelMA-HA hydrogels

We have examined the effects of surface nanotopography and hyaluronic acid (HA) on in vitro chondrogenesis of dental pulp stem cells (DPSCs). Ultraviolet-assisted capillary force lithography was employed to fabricate well-defined nanostructured scaffolds of composite PEG-GelMA-HA hydrogels that consist of poly(ethylene glycol) dimethacrylate (PEGDMA), methacrylated gelatin (GelMA), and HA. Using this microengineered platform, we first demonstrated that DPSCs formed three-dimensional spheroids, which provide an appropriate environment for in vitro chondrogenic differentiation. We also found that DPSCs cultured on nanopatterned PEG-GelMA-HA scaffolds showed a significant upregulation of the chondrogenic gene markers (Sox9, Alkaline phosphatase, Aggrecan, Procollagen type II, and Procollagen type X), while downregulating the pluripotent stem cell gene, Nanog, and epithelial-mesenchymal genes (Twist, Snail, Slug) compared with tissue culture polystyrene-cultured DPSCs. Immunocytochemistry showed more extensive deposition of collagen type II in DPSCs cultured on the nanopatterned PEG-GelMA-HA scaffolds. These findings suggest that nanotopography and HA provide important cues for promoting chondrogenic differentiation of DPSCs.

Biological responses of human gingival fibroblasts (HGFs) in an innovative co-culture model with Streptococcus mitis to thermosets coated with a silver polysaccharide antimicrobial system

This study sought to evaluate the in vitro biological response of human gingival fibroblasts (HGFs) co-coltured with Streptococcus mitis to bisphenol A glycidylmethacrylate/triethylene glycol dimethacrylate (BisGMA/TEGDMA) thermosets coated with Chitlac-nAg, a nanocomposite system with antimicrobial properties. To avoid bacterial adhesion to dental devices and to reduce cytotoxicity against eukaryotic cells, we coated BisGMA/TEGDMA methacrylic thermosets with a new material, Chitlac-nAg, formed by stabilizing silver nanoparticles, which have well-known antimicrobial properties, with a polyelectrolyte solution containing Chitlac. Cytotoxicity, cell morphology, cell migration and inflammatory interleukine-6 (IL-6) and prostaglandin E2 (PGE2) secretion were evaluated. Our results showed that the cytotoxicity exerted on HGFs by our nanocomposite material was absent in our co-culture model, where fibroblasts are able to adhere and migrate. After 24 h thermosets coated with Chitlac as well as those coated with Chitlac-nAg exerted a minimal cytotoxic effect on HGFs, while after 48 h LDH release rises up 20%. Moreover the presence of S. mitis reduced this release in a greater amount with Chitlac-nAg coated thermosets. The secretion of IL-6 was significant in both Chitlac and Chitlac-nAg coated thermosets, but PGE2 production was minimal, suggesting that the IL-6 production was not related to an inflammatory response. Co-culture and the addiction of saliva did not influence IL-6 and PGE2 secretion. Data obtained in the present work suggest that Chitlac n-Ag coated thermosets could significantly improve the success rates of restorative dentistry, since they limit bacterial adhesion and are not toxic to HGFs.

The substrate-dependent regeneration capacity of mesenchymal stem cell spheroids derived on various biomaterial surfaces

ADSC spheroids derived on various biomaterials present different in vitro properties, which may explain their different efficacies in cartilage repair.

Human oral mucosa and gingiva: a unique reservoir for mesenchymal stem cells

Mesenchymal stem cells (MSCs) represent a heterogeneous population of progenitor cells with self-renewal and multipotent differentiation potential. Aside from their regenerative role, extensive in vitro and in vivo studies have demonstrated that MSCs are capable of potent immunomodulatory effects on a variety of innate and adaptive immune cells. In this article, we will review recent experimental studies on the characterization of a unique population of MSCs derived from human oral mucosa and gingiva, especially their immunomodulatory and anti-inflammatory functions and their application in the treatment of several in vivo models of inflammatory diseases. The ease of isolation, accessible tissue source, and rapid ex vivo expansion, with maintenance of stable stem-cell-like phenotypes, render oral mucosa- and gingiva-derived MSCs a promising alternative cell source for MSC-based therapies.

The calcium-dependent regulation of spheroid formation and cardiomyogenic differentiation for MSCs on chitosan membranes

Mesenchymal stem cells (MSCs) were recently found to form three-dimensional (3D) multicellular spheroids on chitosan membranes. The exact mechanism of spheroid formation, however, remains unclear. In this study, the regulation of spheroid formation for adipose derived adult stem cells (ADAS) grown on chitosan membranes was examined. By varying the membrane thickness, calcium concentration in culture medium, and acetylation extent of chitosan, the physico-chemical characteristics of chitosan that modulated spheroid formation was elucidated. The capacity of cardiomyogenic differentiation was further evaluated. Results suggested that the calcium binding capacity of chitosan may affect the cell-substrate and cell-cell interactions and critically influence the dynamics of spheroid formation. The intracellular calcium level was elevated for ADAS spheroids on chitosan. Chitosan-bound calcium was observed to enter the cells. The expression of N-cadherin was upregulated for ADAS spheroids on chitosan, evidenced by quantitative RT-PCR and Western blot. After the induction by 5-aza, the expression levels of cardiac marker genes (Gata4, Nkx2.5, Tnnt2, and Myh6) were remarkably enhanced (about four-fold) for ADAS on chitosan vs. tissue culture polystyrene or polyvinyl alcohol. Immunofluorescence staining confirmed the expression of cardiac-associated tight junction protein ZO-1 for ADAS grown on chitosan membranes. The gene expression of Wnt11 was significantly upregulated for ADAS spheroids on chitosan at 3 days and 12 days. We suggested that Wnt11 may be involved in the spheroid formation and cardiomyogenic differentiation of MSCs on chitosan membranes. Spheroids formed on the acetylated chitosan or polyvinyl alcohol membranes failed to show such behavior. The properties of MSC spheroids were therefore determined by the culture substrate.

Adhesive and mechanical regulation of mesenchymal stem cell differentiation in human bone marrow and periosteum-derived progenitor cells

It has previously been demonstrated that cell shape can influence commitment of human bone marrow-derived mesenchymal stem cells (hBMCs) to adipogenic, osteogenic, chondrogenic, and other lineages. Human periosteum-derived cells (hPDCs) exhibit multipotency similar to hBMCs, but hPDCs may offer enhanced potential for osteogenesis and chondrogenesis given their apparent endogenous role in bone and cartilage repair in vivo. Here, we examined whether hPDC differentiation is regulated by adhesive and mechanical cues comparable to that reported for hBMC differentiation. When cultured in the appropriate induction media, hPDCs at high cell seeding density demonstrated enhanced levels of adipogenic or chondrogenic markers as compared with hPDCs at low cell seeding density. Cell seeding density correlated inversely with projected area of cell spreading, and directly limiting cell spreading with micropatterned substrates promoted adipogenesis or chondrogenesis while substrates promoting cell spreading supported osteogenesis. Interestingly, cell seeding density influenced differentiation through both changes in cell shape and non-shape-mediated effects: density-dependent adipogenesis and chondrogenesis were regulated primarily by cell shape whereas non-shape effects strongly influenced osteogenic potential. Inhibition of cytoskeletal contractility by adding the Rho kinase inhibitor Y27632 further enhanced adipogenic differentiation and discouraged osteogenic differentiation of hPDCs. Together, our results suggest that multipotent lineage decisions of hPDCs are impacted by cell adhesive and mechanical cues, though to different extents than hBMCs. Thus, future studies of hPDCs and other primary stem cell populations with clinical potential should consider varying biophysical metrics for more thorough optimization of stem cell differentiation.