Matrix Topographical Cue-Mediated Myogenic Differentiation of Human Embryonic Stem Cell Derivatives.

Biomaterials varying in physical properties, chemical composition and biofunctionalities can be used as powerful tools to regulate skeletal muscle-specific cellular behaviors, including myogenic differentiation of progenitor cells. Biomaterials with defined topographical cues (e.g., patterned substrates) can mediate cellular alignment of progenitor cells and improve myogenic differentiation. In this study, we employed soft lithography techniques to create substrates with microtopographical cues and used these substrates to study the effect of matrix topographical cues on myogenic differentiation of human embryonic stem cell (hESC)-derived mesodermal progenitor cells expressing platelet-derived growth factor receptor alpha (PDGFRA). Our results show that the majority (>80%) of PDGFRA+ cells on micropatterned polydimethylsiloxane (PDMS) substrates were aligned along the direction of the microgrooves and underwent robust myogenic differentiation compared to those on non-patterned surfaces. Matrix topography-mediated alignment of the mononucleated cells promoted their fusion resulting in mainly (~86%⁻93%) multinucleated myotube formation. Furthermore, when implanted, the cells on the micropatterned substrates showed enhanced in vivo survival (>5⁻7 times) and engraftment (>4⁻6 times) in cardiotoxin-injured tibialis anterior (TA) muscles of NOD/SCID mice compared to cells cultured on corresponding non-patterned substrates.

WNT3A promotes myogenesis of human embryonic stem cells and enhances in vivo engraftment.

The ability of human embryonic stem cells (hESCs) to differentiate into skeletal muscle cells is an important criterion in using them as a cell source to ameliorate skeletal muscle impairments. However, differentiation of hESCs into skeletal muscle cells still remains a challenge, often requiring introduction of transgenes. Here, we describe the use of WNT3A protein to promote in vitro myogenic commitment of hESC-derived cells and their subsequent in vivo function. Our findings show that the presence of WNT3A in culture medium significantly promotes myogenic commitment of hESC-derived progenitors expressing a mesodermal marker, platelet-derived growth factor receptor-α (PDGFRA), as evident from the expression of myogenic markers, including DES, MYOG, MYH1, and MF20. In vivo transplantation of these committed cells into cardiotoxin-injured skeletal muscles of NOD/SCID mice reveals survival and engraftment of the donor cells. The cells contributed to the regeneration of damaged muscle fibers and the satellite cell compartment. In lieu of the limited cell source for treating skeletal muscle defects, the hESC-derived PDGFRA(+) cells exhibit significant in vitro expansion while maintaining their myogenic potential. The results described in this study provide a proof-of-principle that myogenic progenitor cells with in vivo engraftment potential can be derived from hESCs without genetic manipulation.

Mineralized gelatin methacrylate-based matrices induce osteogenic differentiation of human induced pluripotent stem cells.

Human induced pluripotent stem cells (hiPSC) are a promising cell source with pluripotency and self-renewal properties. Design of simple and robust biomaterials with an innate ability to induce lineage-specificity of hiPSC is desirable to realize their application in regenerative medicine. In this study, the potential of biomaterials containing calcium phosphate minerals to induce osteogenic differentiation of hiPSC was investigated. hiPSC cultured using mineralized gelatin methacrylate-based matrices underwent osteogenic differentiation ex vivo, in both two-dimensional and three-dimensional cultures, in growth medium devoid of any osteogenic-inducing chemical components or growth factors. The findings that osteogenic differentiation of hiPSC can be achieved through biomaterial-based cues alone present new avenues for personalized regenerative medicine. Such biomaterials that could not only act as structural scaffolds, but could also provide tissue-specific functions such as directing stem cell differentiation commitment, have great potential in bone tissue engineering.

Correction: Directed In Vitro Myogenesis of Human Embryonic Stem Cells and Their In Vivo Engraftment.

[This corrects the article on p. e72023 in vol. 8.].

Directed in vitro myogenesis of human embryonic stem cells and their in vivo engraftment.

Development of human embryonic stem cell (hESC)-based therapy requires derivation of in vitro expandable cell populations that can readily differentiate to specified cell types and engraft upon transplantation. Here, we report that hESCs can differentiate into skeletal muscle cells without genetic manipulation. This is achieved through the isolation of cells expressing a mesodermal marker, platelet-derived growth factor receptor-α (PDGFRA), following embryoid body (EB) formation. The ESC-derived cells differentiated into myoblasts in vitro as evident by upregulation of various myogenic genes, irrespective of the presence of serum in the medium. This result is further corroborated by the presence of sarcomeric myosin and desmin, markers for terminally differentiated cells. When transplanted in vivo, these pre-myogenically committed cells were viable in tibialis anterior muscles 14 days post-implantation. These hESC-derived cells, which readily undergo myogenic differentiation in culture medium containing serum, could be a viable cell source for skeletal muscle repair and tissue engineering to ameliorate various muscle wasting diseases.