Modulating human mesenchymal stem cell plasticity using micropatterning technique

Liquefied capsules containing nanogrooved microdiscs and umbilical cord-derived cells for bone tissue engineering

Background

Surface topography has been shown to influence cell behavior and direct stromal cell differentiation into distinct lineages. Whereas this phenomenon has been verified in two-dimensional cultures, there is an urgent need for a thorough investigation of topography's role within a three-dimensional (3D) environment, as it better replicates the natural cellular environment.

Methods

A co-culture of Wharton's jelly-derived mesenchymal stem/stromal cells (WJ-MSCs) and human umbilical vein endothelial cells (HUVECs) was encapsulated in a 3D system consisting of a permselective liquefied environment containing freely dispersed spherical microparticles (spheres) or nanogrooved microdiscs (microdiscs). Microdiscs presenting 358 ± 23 nm grooves and 944 ± 49 nm ridges were produced via nanoimprinting of spherical polycaprolactone microparticles between water-soluble polyvinyl alcohol counter molds of nanogrooved templates. Spheres and microdiscs were cultured in vitro with umbilical cord-derived cells in a basal or osteogenic medium within liquefied capsules for 21 days.

Results

WJ-MSCs and HUVECs were successfully encapsulated within liquefied capsules containing spheres and microdiscs, ensuring high cellular viability. Results show an enhanced osteogenic differentiation in microdiscs compared to spheres, even in basal medium, evidenced by alkaline phosphatase activity and osteopontin expression.

Conclusions

This work suggests that the topographical features present in microdiscs induce the osteogenic differentiation of adhered WJ-MSCs along the contact guidance, without additional differentiation factors. The developed 3D bioencapsulation system comprising topographical features might be suitable for bone tissue engineering approaches with minimum in vitro manipulation.

Bioactive micropatterned platform to engineer myotube-like cells from stem cells

Skeletal muscle has the capacity to repair and heal itself after injury. However, this self-healing ability is diminished in the event of severe injuries and myopathies. In such conditions, stem cell-based regenerative treatments can play an important part in post injury restoration. We herein report the development of a bioactive (integrin-β1 antibody immobilized) gold micropatterned platform to promote human mesenchymal stem cells (hMSCs) differentiation into the myotube-like cells. hMSCs grown on bioactive micropattern differentiated into the myotube-like cells within two weeks. Further, up-regulation of myogenic markers, multi-nucleated state with continuous actin cytoskeleton and absence of proliferation marker confirmed the formation of myotube-like cells on bioactive micropattern. Prominent expression of elongated integrin-β1 focal adhesions (ITG-β1 FAs) and development of anisotropic stress fibres in those differentiated cells elucidated their importance in stem cell myogenesis. Together these findings delineate the synergistic role of engineered cell anisotropy and ITG-β1 mediated signaling in the development of myotube-like cells from hMSCs.

Contact guidance for cardiac tissue engineering using 3D bioprinted gelatin patterned hydrogel

Here, we have developed a 3D bioprinted microchanneled gelatin hydrogel that promotes human mesenchymal stem cell (hMSC) myocardial commitment and supports native cardiomyocytes (CMs) contractile functionality. Firstly, we studied the effect of bioprinted microchanneled hydrogel on the alignment, elongation, and differentiation of hMSC. Notably, the cells displayed well defined F-actin anisotropy and elongated morphology on the microchanneled hydrogel, hence showing the effects of topographical control over cell behavior. Furthermore, the aligned stem cells showed myocardial lineage commitment, as detected using mature cardiac markers. The fluorescence-activated cell sorting analysis also confirmed a significant increase in the commitment towards myocardial tissue lineage. Moreover, seeded CMs were found to be more aligned and demonstrated synchronized beating on microchanneled hydrogel as compared to the unpatterned hydrogel. Overall, our study proved that microchanneled hydrogel scaffold produced by 3D bioprinting induces myocardial differentiation of stem cells as well as supports CMs growth and contractility. Applications of this approach may be beneficial for generating in vitro cardiac model systems to physiological and cardiotoxicity studies as well as in vivo generating custom designed cell impregnated constructs for tissue engineering and regenerative medicine applications.

Combined effects of multi-scale topographical cues on stable cell sheet formation and differentiation of mesenchymal stem cells

To decipher specific cell responses to diverse and complex in vivo signals, it is essential to emulate specific surface chemicals, extra cellular matrix (ECM) components and topographical signals through reliable and easily reproducible in vitro systems.

Micropatterning strategies to engineer controlled cell and tissue architecture in vitro

Micropatterning strategies, which enable control over cell and tissue architecture in vitro, have emerged as powerful platforms for modelling tissue microenvironments at different scales and complexities. Here, we provide an overview of popular micropatterning techniques, along with detailed descriptions, to guide new users through the decision making process of which micropatterning procedure to use, and how to best obtain desired tissue patterns. Example techniques and the types of biological observations that can be made are provided from the literature. A focus is placed on microcontact printing to obtain co-cultures of patterned, confluent sheets, and the challenges associated with optimizing this protocol. Many issues associated with microcontact printing, however, are relevant to all micropatterning methodologies. Finally, we briefly discuss challenges in addressing key limitations associated with current micropatterning technologies.

hMSCs bridging across micro-patterned grooves

hMSCs spanned across a groove with 100 μm width.