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Genome-wide gene expression analyses during chondrogenic differentiation of hiPSC. A) Hierarchical clustering and representative heatmap of genome-wide gene expression at different stages during hiPSC differentiation to hiChondrocytes and comparison with undifferentiated hiPSC and adult chondrocytes. B) Top gene ontology terms significantly enriched at different stages during chondrogenic differentiation of hiPSCs. C) Gene expression for characteristic markers of mesodermal subtypes and posterior, mid-, anterior, and late PS observed at an early stage (d 4) during chondrogenic differentiation of hiPSCs. D–F) Expression of known Sox9-regulated genes including transcription factors, signaling molecules, and ECM proteins in the Sox9 low and Sox9 high populations induced during chondrogenic differentiation of hiPSCs. Data presented as means 6 SE for gene expression vs. hiPSCs (n = 2 biologic replicates).
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Regeneration of human cartilage is inherently inefficient; an abundant autologous source, such as human induced pluripotent stem cells (hiPSCs), is therefore attractive for engineering cartilage. We report a growth factor-based protocol for differentiating hiPSCs into articular-like chondrocytes (hiChondrocytes) within 2 weeks, with an overall effi...
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... dye-binding assay with shark CS (Sigma-Aldrich) as the standard. GAG content of the acellular hydrogels was determined as a negative control and subtracted from the amount of GAG released by the encapsulated cells during the 4 wk of culture. . Clustering analysis performed on these combined gene lists enabled the generation of the heat map in Fig. 4. Network analysis of the genes that had a 1.5-fold or greater upregula- tion in expression at each stage of differentiation when com- pared to the hiPSCs (the hiPSCs were compared to adult chondrocytes) was performed using MetaCore. Raw microarray data was uploaded to the Gene Expression Omnibus [accession number: GSE62914; National ...
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... found to be highly ex- pressed, indicating that the differentiation was directed toward an articular chondrocyte fate rather than a growth plate chondrocyte. Moreover, hiChondrocytes maintained the coexpression of Sox9 and Col II upon multiple rounds of cell passaging after 14 d of differentiation as well as post- cryopreservation (Supplemental Fig. S4A). Taken together, these findings demonstrate that the reported differentiation method is efficient and ...
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... or type X collagen (Col10a1), showing a lack of both characteristic fibrocartilage and hypertrophic mark- ers. Quantification of the fluorescence intensity using Im- age J (National Institutes of Health, Bethesda, MD, USA) determined the staining intensity for type II collagen to be 20-fold higher than that of type I collagen (Supplemental Fig. ...
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... analysis for Sox9 at different times in the differentiation protocol during the stepwise growth-factor treatment for 14 d and quantified the Sox9 low and Sox9 high populations (Fig. 3A and Supple- mental Fig. S6B). The cells are exclusively Sox9 low at d 4 and 7 and were exclusively Sox9 high after passage 1. The repre- sentative Supplemental Fig. S6B demonstrates 3 batches (1, 3, and 4) from lentivirally generated hiPSCs and 2 batches (7 and 10) from retrovirally generated hiPSCs. Differentiation in all the batches is consistent with a 5-9% variation in the overall Sox9-expressing population at d 4, 9, and 14 that eventually gave rise to a very homogenous Sox9 high population after the first passage of cells. After ...
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... were similar to adult chondrocytes, but distinct from the intermediate differentiating pop- ulations and hiPSCs (Supplemental Fig. S8C). For the ini- tial analyses, we identified a subset of 270 genes, including the known critical markers for pluripotency, cartilage dif- ferentiation, and chondrocytes, as well as early mesoder- mal genes (Fig. 4A). Upon differentiation, gene expression of pluripotency markers, including SOX2, TET1, OCT4, NANOG, and SALL4, was immediately down-regulated, as observed clearly by d 4, concurrent with an increase in expression of mesodermal genes, including NOTCH1, HAND1, TBX20, TBX3, LEF1, NKX2.5, and ISL1, in the intermediate stages of ...
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... regulators to be enriched in hiPSCs, whereas cell-matrix interactors, cartilage development, and bone ossification and remodeling pathways were enriched in adult chondrocytes. For the intermediate stages, regu- lation of epithelial-to-mesenchymal transition, cell-matrix interactions, and BMP/TGFb signaling were the significant pathways identified (Fig. 4B). It has been an unresolved question whether the primitive streak (PS) mesodermal induction consists of a common mesenchymal progenitor or distinct progenitor cells destined for the downstream lineages. In a recent elegant study, investigators addressed this complex question and suggested the existence of multiple distinct progenitors, ...
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... further identifying the spatial and temporal patterns of genes that particularly charac- terize a prechondrogenic progenitor (31). To test whether our differentiation protocol leads to an enrichment of the newly described prechondrogenic me- sodermal progenitors, we sought to compare the gene expression of different mesodermal developmental genes (Fig. 4C). Indeed, we observed that, when compared to hiPSCs, the early mesodermal populations at d 4 of dif- ferentiation showed an enrichment for the genes associ- ated with posterior PS lateral plate mesoderm that later matures into the prechondrogenic mesoderm, whereas the genes associated with the anterior PS that develops into cardiac ...
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... as containing Sox9 interaction sites in a chondrogenic rat sarcoma cell line by chromatin immunoprecipitation, fol- lowed by global array (ChIP-chip) (33) in the Sox9 low mesodermal population and the Sox9 high chondrocytes. We divided the Sox9-regulated genes into 3 groups: tran- scription factors, signaling molecules, and ECM proteins ( Fig. 4D-F). In the group of transcription factors (Fig. 4D), expression of LEF1, which interacts with b-catenin under Wnt stimulation (32), was high in the Sox9 low population (d 4 and 9), whereas RUNX2, PRRX1 (34), and the tran- scriptional coactivator PGC-1a (35) expression was high in Sox9 high hiChondrocytes. In the signaling molecules ...
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... chondrogenic rat sarcoma cell line by chromatin immunoprecipitation, fol- lowed by global array (ChIP-chip) (33) in the Sox9 low mesodermal population and the Sox9 high chondrocytes. We divided the Sox9-regulated genes into 3 groups: tran- scription factors, signaling molecules, and ECM proteins ( Fig. 4D-F). In the group of transcription factors (Fig. 4D), expression of LEF1, which interacts with b-catenin under Wnt stimulation (32), was high in the Sox9 low population (d 4 and 9), whereas RUNX2, PRRX1 (34), and the tran- scriptional coactivator PGC-1a (35) expression was high in Sox9 high hiChondrocytes. In the signaling molecules group, BMP2, BMP4, and TGFb1 were highly expressed in ...
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... and the tran- scriptional coactivator PGC-1a (35) expression was high in Sox9 high hiChondrocytes. In the signaling molecules group, BMP2, BMP4, and TGFb1 were highly expressed in Sox9 low but were down-regulated in the Sox9 high hiChon- drocytes, whereas CD44, integrin, and epidermal growth factor receptor were highly expressed in those cells (Fig. 4E). We noted especially that the ECM proteins in the third group (Fig. 4F) exhibited the most significant in- crease in Sox9-regulated ECM genes, including COL3A1, BGN, COL11A1, DCN, ADAMTS5, COL2A1, ASPN, and OGN in Sox9 high hiChondrocytes. The ECM proteins encoded by these genes are critical for human articular cartilage ...
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... in Sox9 high hiChondrocytes. In the signaling molecules group, BMP2, BMP4, and TGFb1 were highly expressed in Sox9 low but were down-regulated in the Sox9 high hiChon- drocytes, whereas CD44, integrin, and epidermal growth factor receptor were highly expressed in those cells (Fig. 4E). We noted especially that the ECM proteins in the third group (Fig. 4F) exhibited the most significant in- crease in Sox9-regulated ECM genes, including COL3A1, BGN, COL11A1, DCN, ADAMTS5, COL2A1, ASPN, and OGN in Sox9 high hiChondrocytes. The ECM proteins encoded by these genes are critical for human articular cartilage ...
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... that had a persistent high expression of Sox9 (36). The hiChon- drocytes generated are stable and do not dedifferentiate upon cryopreservation, as in up to 3 passages of monolayer culture of hiChondrocytes in vitro, the process of freezing and thawing did not diminish the expression of the chondrogenic markers, Sox9 and Col2a1 (Supplemental Fig. S4A). In addition, the hiChondrocytes had a pro- liferative advantage over adult chondrocytes that could be beneficial for their expansion for research or therapeutic applications (Supplemental Fig. ...
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... EBs toward the mesoderm. Using our differentiation protocol, we have identified that the pos- terior PS markers, as was recently described to characterize a prechondrogenic mesodermal population (19), were markedly induced in the early populations during hiPSC differentiation (d 4), whereas the anterior PS/cardiac mesodermal markers were reduced (Fig. 4C). These results highlight that the combination of Wnt3A, Activin A, and the ROCK inhibitor Y27632 led to a preferential enrich- ment of prechondrogenic mesoderm at the onset of hiPSC differentiation in our ...
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... the cellular differentiation process is homogenous and that the maturation of Sox9 low to Sox9 high expression is a distinct step in chondrogenic differentiation. In addition, our study shows that Sox9 has a distinct set of binding targets when its levels are low and that it can especially activate these target genes (like LEF and BMP4, as in Fig. 4D, E) only at low levels. As expected, a different set of genes appeared to be activated when the levels were high (Fig. 4F), thereby providing new and interesting insights into the gene networks regulated by Sox9. In future studies, it will be interesting to illuminate the differences in the cofactors and binding targets when Sox9 ...
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... step in chondrogenic differentiation. In addition, our study shows that Sox9 has a distinct set of binding targets when its levels are low and that it can especially activate these target genes (like LEF and BMP4, as in Fig. 4D, E) only at low levels. As expected, a different set of genes appeared to be activated when the levels were high (Fig. 4F), thereby providing new and interesting insights into the gene networks regulated by Sox9. In future studies, it will be interesting to illuminate the differences in the cofactors and binding targets when Sox9 levels are low or high, to get detailed mechanistic information about Sox9 ...
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The development of induced pluripotent stem cells has brought unlimited possibilities to the field of regenerative medicine. This could be ideal for treating osteoarthritis and other skeletal diseases, because the current procedures tend to be short-term solutions. The usage of induced pluripotent stem cells in the cell-based regeneration of cartil...
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... The abundant deposition of GAGs and collagen type II, in the absence of collagen type I, surpasses the quality of matrix production that has previously been shown by equine and human primary chondrocytes encapsulated in GelMA (Boere et al., 2014;Visser et al., 2015b;Mouser et al., 2016;Hölzl et al., 2022). This difference in metabolic performance could be attributed to the age of the chondrocytes used in each study as older primary cells tend to produce a less functional matrix (Loeser, 2009;Lee et al., 2015;Castro-Viñuelas et al., 2020). In corroboration with our observation that more matrix is deposited in our setup than with primary chondrocytes, we also obtained a higher compressive modulus (250 kPa; see Supplementary Figure S3) in a shorter in vitro culture period than previously reported, which is supported by the fact that the compression modulus is correlated with the GAG content of tissue engineered constructs (Pfeiffer et al., 2008;Levato et al., 2017). ...
Osteochondral defects are deep joint surface lesions that affect the articular cartilage and the underlying subchondral bone. In the current study, a tissue engineering approach encompassing individual cells encapsulated in a biocompatible hydrogel is explored in vitro and in vivo. Cell-laden hydrogels containing either human periosteum-derived progenitor cells (PDCs) or human induced pluripotent stem cell (iPSC)-derived chondrocytes encapsulated in gelatin methacryloyl (GelMA) were evaluated for their potential to regenerate the subchondral mineralized bone and the articular cartilage on the joint surface, respectively. PDCs are easily isolated and expanded progenitor cells that are capable of generating mineralized cartilage and bone tissue in vivo via endochondral ossification. iPSC-derived chondrocytes are an unlimited source of stable and highly metabolically active chondrocytes. Cell-laden hydrogel constructs were cultured for up to 28 days in a serum-free chemically defined chondrogenic medium. On day 1 and day 21 of the differentiation period, the cell-laden constructs were implanted subcutaneously in nude mice to evaluate ectopic tissue formation 4 weeks post-implantation. Taken together, the data suggest that iPSC-derived chondrocytes encapsulated in GelMA can generate hyaline cartilage-like tissue constructs with different levels of maturity, while using periosteum-derived cells in the same construct type generates mineralized tissue and cortical bone in vivo. Therefore, the aforementioned cell-laden hydrogels can be an important part of a multi-component strategy for the manufacturing of an osteochondral implant.
... Lee et al.503 added WNT3A, Activin A, FGF-2, and BMP-4 on different days to differentiate 504 hiPSCs to embryoid bodies and then mesoderm. In this study, for chondrogenesis 505 induction, follistatin, NT4, and GDF5 were used, and chondrocytes formation was 506 observed after 14 days(Lee et al. 2015). In another study, Adkar et al. added 507 Activin A, CHIR99021, and the FGF-2 succeeded by BMP inhibitor (dorsomorphin) and TGF-b inhibitor (SB505124) to induce mesodermal lineage differentiation and 509 sclerotome formation and then applied BMP-4 to hiPSCs for prechondrogenesis510 followed by addition of TGF-b3 for mature chondrogenesis (Adkar et al. 2019). ...
For both academics and clinicians, the repair and regeneration of articular cartilage have offered a challenging array of issues. Injuries to articular cartilage have a poor chance of healing since it is an avascular tissue. Small defects may eventually heal on their own without treatment, but the repair tissue is inferior to the body’s own hyaline cartilage because it is made of fibrocartilage. Due to its regenerative capabilities, the idea of stem cell therapy has sparked intense research into its potential application for treating cartilage lesions, including OA. The purpose of this chapter is to present a perspective on stem cell-based therapy for cartilage repair and to highlight recent developments in advanced cell therapy, in particular, the use of embryonic stem cells, mesenchymal stem cells, and induce pluripotent stem cells for treating diseases associated with cartilage defects, particularly OA.KeywordsStem cellRegenerationCartilageOsteoarthritis
... e II positive matrix is observed (Hall et al., 2021;Tam et al., 2021;Yamashita et al., 2015). Authors have shown the in vitro and in vivo cartilage-producing potential of iPSC-derived chondrocytes in a scaffold-free approach, or in combination with hydrogels, such as alginate, chondroitin sulfate PEG, and nanofibrillated cellulose (Ko et al., 2014;J. Lee et al., 2015;Nakamura et al., 2021;Nguyen et al., 2017;Yamashita et al., 2015). However, to our knowledge, the combination of a GelMA hydrogel with iPSC-derived chondrocytes has not yet been explored. In this study, we therefore investigated the in vitro chondrogenic differentiation potential of iPSC-derived chondrocytes in a GelMA hydrogel and evalu ...
Articular cartilage defects have limited healing potential and, when left untreated, can lead to osteoarthritis. Tissue engineering focuses on regenerating the damaged joint surface, preferably in an early stage. Here, we investigate the regenerative potential of three‐dimensional (3D) constructs consisting of human induced pluripotent stem cell (iPSC)‐derived chondrocytes in gelatin methacryloyl (GelMA) hydrogel for stable hyaline cartilage production. iPSC‐derived chondrocytes are encapsulated in GelMA hydrogel at low (1 × 10⁷ ml⁻¹) and high (2 × 10⁷ ml⁻¹) density. In a conventional medium, GelMA hydrogel supports the chondrocyte phenotype, as opposed to cells cultured in 3D in absence of hydrogel. Moreover, encapsulated iPSC‐derived chondrocytes preserve their in vivo matrix formation capacity after 21 days in vitro. In differentiation medium, hyaline cartilage‐like tissue forms after 21 days, demonstrated by highly sulfated glycosaminoglycans and collagen type II. Matrix deposition is delayed at low encapsulation density, corroborating with lower transcript levels of COL2A1. An ectopic assay in nude mice demonstrates further maturation of the matrix deposited in vitro. Direct ectopic implantation of iPSC‐derived chondrocyte‐laden GelMA, without in vitro priming, also generates hyaline cartilage‐like tissue, albeit less mature. Since it is unclear what maturity upon implantation is desired for joint surface regeneration, this is an attractive technology to generate immature and more mature hyaline cartilage‐like tissue.
... In the same year, Lee's team presented another suitable protocol based on Oldershaw et al., with a few modifications [99,108]. In the early stages, instead of a monolayer culture, an EB approach with the supplementation of a ROCK inhibitor (Y27632) was used, resulting in the increased viability of cells and the enhanced chondrogenic potential of differentiated cells by a high number of SOX9-positive cells. ...
The development of induced pluripotent stem cells has brought unlimited possibilities to the field of regenerative medicine. This could be ideal for treating osteoarthritis and other skeletal diseases, because the current procedures tend to be short-term solutions. The usage of induced pluripotent stem cells in the cell-based regeneration of cartilage damages could replace or improve on the current techniques. The patient's specific non-invasive collection of tissue for reprogramming purposes could also create a platform for drug screening and disease modelling for an overview of distinct skeletal abnormalities. In this review, we seek to summarise the latest achievements in the chondrogenic differentiation of pluripotent stem cells for regenerative purposes and disease modelling.
... Induced NSCs are transdifferentiated from somatic cells (Meyer et al., 2014;Lee et al., 2015;Wang et al., 2013;Zhu et al., 2014;Shahbazi et al., 2016) through different approaches, including transitory expression of Yamanaka's TFs followed by rapid neural induction, direct overexpression of proneurogenic factors (through TFs and/or cocktail of small molecules), such SOX2 alone, OCT4 alone, or the zinc-finger protein Zfp521. Induced NSCs can be expanded, cryopreserved, or differentiated into mature astrocytes through conventional techniques. ...
... To induce chondrogenesis, follistatin, NT4, and GDF5 were further added at different time-points as shown in Fig. 7.2. After 14 days, stable chondrocytes were formed (Lee et al., 2015) that could be expanded for multiple passages without dedifferentiation. Similarly, Adkar and co-workers applied Activin A, CHIR99021, and the FGF-2 succeeded by BMP inhibitor (dorsomorphin) and TGF-b inhibitor (SB505124). ...
... hyaline-like-cartilaginous tissues in 5 weeks. In another study, our lab utilized a biomimetic hydrogel composed of chondroitin sulfate and poly(ethylene glycol), CS-PEG (Lee et al., 2015). Chondroitin sulfate (CS) which is a sulfated GAG, was incorporated in the hydrogel since it is one of the major components of cartilage ECM. ...
This chapter briefly describes the differentiation of keratinocytes from their precursors to mature cells in the epidermis of the skin and the protective role of the epidermis. In certain genetic skin disorders, the differentiation and function of keratinocytes are impaired. Since primary keratinocytes from patients with those disorders are not always available, there has been much interest to differentiate functional keratinocytes from human induced pluripotent stem cells (hiPSCs) for research and clinical use. Prior to the arrival of iPSC technologies research on keratinocyte differentiation was conducted with embryonic stem cells (ESCs). Similar to ESCs, hiPSCs can give rise to virtually any cell type and can be genetically corrected, allowing the development of therapies for many incurable disorders, including skin diseases. This chapter introduces significant findings that led to the development of keratinocyte differentiation protocols from hiPSCs that either use embryoid bodies, hiPSC colonies, or singularized hiPSCs. We also discuss the potential of skin-derived precursor cells and direct reprogramming of keratinocytes from fibroblasts or adipocytes. The use of hiPSC-derived keratinocytes for patient treatment is still very limited due to safety concerns inherent to the stem cell nature of hiPSCs. However, keratinocyte derivation from hiPSCs is an important research tool for clinical and basic research, not only when patient cells are unavailable. Disease mutations can be repaired by gene editing or can be introduced into healthy cells for research purposes thus creating isogenic cell lines with identical genetic background that differ only by the disease mutation. hiPSCs can be differentiated into typical cell types found in skin and are therefore ideal to generate organotypic skin equivalents for disease research, pharmacologic or cosmetic safety studies, and for toxicological studies. Recently, three-dimensional organotypic skin constructs can be grown in microfluidic devices (skin-on-chip) equipped with biosensors for physiologic and mechanical studies.
... Adult normal chondrocytes were purchased from Cell Applications (N1: 56 years of age, male) and Articular Engineering (N2: 63 years of age, male; N3: 66 years of age, male) and expanded for a limited number of passages (1)(2)(3)(4) in chondrocyte growth medium. iChondrocytes were generated and cultured as previously described 31 in chondrocyte growth medium (Lonza) on gelatin coated plates. OA chondrocytes were collected from articular cartilage samples obtained from patients with OA (n = 7, 50-70 years of age) during total knee arthroplasty after obtaining informed consent and in accordance with the methods and protocols approved by Institutional Review Board of Stanford University. ...
Changes in the composition and viscoelasticity of the extracellular matrix in load-bearing cartilage influence the proliferation and phenotypes of chondrocytes, and are associated with osteoarthritis. However, the underlying molecular mechanism is unknown. Here we show that the viscoelasticity of alginate hydrogels regulates cellular volume in healthy human chondrocytes (with faster stress relaxation allowing cell expansion and slower stress relaxation restricting it) but not in osteoarthritic chondrocytes. Cellular volume regulation in healthy chondrocytes was associated with changes in anabolic gene expression, in the secretion of multiple pro-inflammatory cytokines, and in the modulation of intracellular calcium regulated by the ion-channel protein transient receptor potential cation channel subfamily V member 4 (TRPV4), which controls the phosphorylation of glycogen synthase kinase 3β (GSK3β), an enzyme with pleiotropic effects in osteoarthritis. A dysfunctional TRPV4–GSK3β pathway in osteoarthritic chondrocytes rendered the cells unable to respond to environmental changes in viscoelasticity. Our findings suggest strategies for restoring chondrocyte homeostasis in osteoarthritis. A dysfunctional TRPV4–GSK3β pathway in osteoarthritic chondrocytes renders the cells unable to respond to viscoelastic changes in the extracellular matrix.
... Studies have demonstrated the induction of PSCs into chondrocytes along the mesodermal or ectomesodermal lineage. For example, several groups have shown that through stepwise induction by growth factors, mesoderm-derived chondrocytes can be generated from hESCs (9)(10)(11) or hiPSCs (12)(13)(14)(15), and these MCs are capable of repairing cartilage lesions in rodent joints (13,14,16). Besides mesodermal derivation, other studies have shown that chondrocytes can be obtained through differentiation of NCCs derived from hESCs (17)(18)(19) or hiPSCs (20) along the ectomesodermal lineage. ...
Generating phenotypic chondrocytes from pluripotent stem cells is of great interest in the field of cartilage regeneration. In this study, we differentiated human induced pluripotent stem cells into the mesodermal and ectomesodermal lineages to prepare isogenic mesodermal cell–derived chondrocytes (MC-Chs) and neural crest cell–derived chondrocytes (NCC-Chs), respectively, for comparative evaluation. Our results showed that both MC-Chs and NCC-Chs expressed hyaline cartilage–associated markers and were capable of generating hyaline cartilage–like tissue ectopically and at joint defects. Moreover, NCC-Chs revealed closer morphological and transcriptional similarities to native articular chondrocytes than MC-Chs. NCC-Ch implants induced by our growth factor mixture demonstrated increased matrix production and stiffness compared to MC-Ch implants. Our findings address how chondrocytes derived from pluripotent stem cells through mesodermal and ectomesodermal differentiation are different in activities and functions, providing the crucial information that helps make appropriate cell choices for effective regeneration of articular cartilage.
... iPSCs potentially can provide an abundant and immune compatible cell source. They are pluripotent in nature, and may provide functional cell types for chondrocyte differentiation [509,510], with the advantage of being able to produce their own matrix, enabling scaffold-free tissue regeneration. However, cell generation is time consuming and expensive, and uncontrolled de-differentiation poses risks for teratogenicity. ...
Stem cells are undifferentiated cells, which possess self-renewal properties and can produce specialized cells of multiple lineages. In addition to other stem cells from various anatomical locations within the maxillofacial complex, the oral cavity harbours both epithelial and mesenchymal stem cells, each suited to approaches for treating or managing a variety of specific conditions encountered in routine clinical oral medicine practice. This chapter focusses on stem cell and regenerative medicine approaches related to oral pathology and oral medicine with particular attention paid to oral mucosal diseases, salivary gland disorders, craniofacial and temporomandibular joint disorders, and orofacial pain conditions. The potential roles of stem cells in highlighting the pathogenesis of these conditions in addition to regenerative strategies for their management are outlined. The role of bioprinting as a potential therapeutic approach for both soft and hard tissue defects is discussed. Finally, the limitations of current approaches to regenerative medicine underpinned by imperfect and incomplete understanding of stem cell niches and their properties are summarized.
... iPSCs potentially can provide an abundant and immune compatible cell source. They are pluripotent in nature, and may provide functional cell types for chondrocyte differentiation [509,510], with the advantage of being able to produce their own matrix, enabling scaffold-free tissue regeneration. However, cell generation is time consuming and expensive, and uncontrolled de-differentiation poses risks for teratogenicity. ...
Stem cell-based therapy is one of the most thriving fields in tissue regenerative therapeutic approaches. Dental stem cells (DSCs), which are originally derived from neural crest and usually are harvested from tissues that are considered as medical waste, hold considerable promise for regeneration of many tissues. Five different types of DSCs have been isolated and characterized: Stem cells derived from dental pulp of permanent teeth (DPSCs) or exfoliated deciduous teeth (SHEDs), stem cells from apical papillae (SCAPs), dental follicle stem cells (DFSCs), and periodontal ligament stem cells (PDLSCs). These DSCs have demonstrated the capability to differentiate toward distinctive cell lines such as chondrogenic, osteogenic, adipogenic, and neurogenic pathways in vitro. Moreover, various studies have shown their potential for regeneration of the dentine–pulp complex, bone, nerve, blood vessels, muscle, cartilage, and adipose tissues. The application of DSCs for regenerative medicine is as yet in its early stage. This chapter will provide insights regarding the progress being made on utilizing DSCs in tissue regeneration.
... 146 While several differentiation strategies have been developed for the generation of chondrocyte-and NP-like cells that could be applied for IVD regeneration, the use of iPSCs for generation of AF-like cells remains to be explored. 146,[149][150][151][152][153][154] Future Directions ...
The intervertebral disc (IVD) is an integral load-bearing tissue that derives its function from its composite structure and extracellular matrix composition. IVD herniations involve the failure of the annulus fibrosus (AF) and the extrusion of the nucleus pulposus beyond the disc boundary. Disc herniations can impinge the neural elements and cause debilitating pain and loss of function, posing a significant burden on individual patients and society as a whole. Patients with persistent symptoms may require surgery; however, surgical intervention fails to repair the ruptured AF and is associated with the risk for re-herniation and further disc degeneration. Given the limitations of AF endogenous repair, many attempts have been made towards the development of effective repair approaches that re-establish IVD function. These methods, however, fail to recapitulate the composition and organization of the native AF, ultimately resulting in inferior tissue mechanics and function over time and high rates of re-herniation. Harnessing the cellular function of cells (endogenous or exogenous) at the repair site through the provision of cell-instructive cues could enhance AF tissue regeneration and, ultimately, improve healing outcomes. Here, we review the diverse approaches that have been developed for AF repair and emphasize the potential for mobilizing the appropriate cellular players at the site of injury to improve AF healing.
