Selection of human induced pluripotent stem cells lines optimization of cardiomyocytes differentiation in an integrated suspension microcarrier bioreactor.

BACKGROUND: The production of large quantities of cardiomyocyte is essential for the needs of cellular therapies. This study describes the selection of a human-induced pluripotent cell (hiPSC) line suitable for production of cardiomyocytes in a fully integrated bioprocess of stem cell expansion and differentiation in microcarrier stirred tank reactor. METHODS: Five hiPSC lines were evaluated first for their cardiac differentiation efficiency in monolayer cultures followed by their expansion and differentiation compatibility in microcarrier (MC) cultures under continuous stirring conditions. RESULTS: Three cell lines were highly cardiogenic but only one (FR202) of them was successfully expanded on continuous stirring MC cultures. FR202 was thus selected for cardiac differentiation in a 22-day integrated bioprocess under continuous stirring in a stirred tank bioreactor. In summary, we integrated a MC-based hiPSC expansion (phase 1), CHIR99021-induced cardiomyocyte differentiation step (phase 2), purification using the lactate-based treatment (phase 3) and cell recovery step (phase 4) into one process in one bioreactor, under restricted oxygen control (< 30% DO) and continuous stirring with periodic batch-type media exchanges. High density of undifferentiated hiPSC (2 ± 0.4 × 106 cells/mL) was achieved in the expansion phase. By controlling the stirring speed and DO levels in the bioreactor cultures, 7.36 ± 1.2 × 106 cells/mL cardiomyocytes with > 80% Troponin T were generated in the CHIR99021-induced differentiation phase. By adding lactate in glucose-free purification media, the purity of cardiomyocytes was enhanced (> 90% Troponin T), with minor cell loss as indicated by the increase in sub-G1 phase and the decrease of aggregate sizes. Lastly, we found that the recovery period is important for generating purer and functional cardiomyocytes (> 96% Troponin T). Three independent runs in a 300-ml working volume confirmed the robustness of this process. CONCLUSION: A streamlined and controllable platform for large quantity manufacturing of pure functional atrial, ventricular and nodal cardiomyocytes on MCs in conventional-type stirred tank bioreactors was established, which can be further scaled up and translated to a good manufacturing practice-compliant production process, to fulfill the quantity requirements of the cellular therapeutic industry.

Influencing the Fate of Cardiac and Neural Stem Cell Differentiation Using Small Molecule Inhibitors of ALK5.

In this study, 50 tri-substituted imidazoles (TIs), which are analogs of the small molecules TA-01 and SB203580, were synthesized and screened for cardiomyogenic activities. Several TIs displayed cardiomyogenic activities when applied during the differentiation from days 3-5. The TIs did not affect the Wnt/ß-catenin pathway during cardiomyogenesis and the likely mechanism of action is through the inhibition of ALK5 of the TGFß pathway. Interestingly, these TIs promoted the neural differentiation of human pluripotent stem cells (hPSCs) with a similar potency to that of the dual SMAD inhibitors SB431542/LDN-193189 when dosed from days 1 to 9. The neural induction activities of the TIs correlated with their ALK5 inhibitory activities. This study reports the discovery of small molecule inhibitors of ALK5, which can promote the differentiation of hPSCs into cardiomyocytes or neural cells depending on the time of dosing, showing potential for the production of clinical-grade cardiac/neural cells for regenerative therapy. Stem Cells Translational Medicine 2018;7:709-720.

Unraveling the Inconsistencies of Cardiac Differentiation Efficiency Induced by the GSK3ß Inhibitor CHIR99021 in Human Pluripotent Stem Cells.

Cardiac differentiation efficiency is hampered by inconsistencies and low reproducibility. We analyzed the differentiation process of multiple human pluripotent stem cell (hPSC) lines in response to dynamic GSK3ß inhibition under varying cell culture conditions. hPSCs showed strong differences in cell-cycle profiles with varying culture confluency. hPSCs with a higher percentage of cells in the G1 phase of the cell cycle exhibited cell death and required lower doses of GSK3ß inhibitors to induce cardiac differentiation. GSK3ß inhibition initiated cell-cycle progression via cyclin D1 and modulated both Wnt signaling and the transcription factor (TCF) levels, resulting in accelerated or delayed mesoderm differentiation. The TCF levels were key regulators during hPSC differentiation with CHIR99021. Our results explain how differences in hPSC lines and culture conditions impact cell death and cardiac differentiation. By analyzing the cell cycle, we were able to select for highly cardiogenic hPSC lines and increase the experimental reproducibility by predicting differentiation outcomes.

Cardiomyocyte differentiation of pluripotent stem cells with SB203580 analogues correlates with Wnt pathway CK1 inhibition independent of p38 MAPK signaling.

Differentiation of human pluripotent stem cells as embryoid bodies (EBs) has been achieved previously with p38alfa MAPK inhibitors such as SB203580 with moderate efficiency of 10-15%. We synthesized and screened 42 compounds that are 2,4,5-trisubstituted azole analogues of SB203580 for efficient cardiomyocyte differentiation. Our screen identified novel compounds that have similar cardiac differentiation activity as SB203580. However, the cardiac differentiation did not correlate with p38alfa MAPK inhibition, indicating an alternative mechanism in cardiac differentiation. Upon profiling several 2,4,5-trisubstituted azole compounds against a panel of 97 kinases we identified several off targets, among them casein kinases 1 (CK1). The cardiomyogenic activities of SB203580 and its analogues showed a correlation with post mesoderm Wnt/beta-catenin pathway inhibition of CK1 epsilon and delta. These findings united the mechanism of 2,4,5-trisubstituted azole with the current theory of Wnt/beta-catenin regulated pathway of cardiac differentiation. Consequently an efficient cardiomyocyte protocol was developed with Wnt activator CHIR99021 and 2,4,5-trisubstituted azoles to give high yields of 50-70% cardiomyocytes and a 2-fold increase in growth.

Tri-substituted imidazole analogues of SB203580 as inducers for cardiomyogenesis of human embryonic stem cells.

The p38α mitogen-activated protein kinase (MAPK) inhibitor SB203580 had been reported to enhance the cardiomyogenesis of human embryonic stem cells (hESCs). To investigate if tri-substituted imidazole analogues of SB203580 are equally effective inducers for cardiomyogenesis of hESCs, and if there is a correlation between p38α MAPK inhibition and cardiomyogenesis, we designed and synthesized a series of novel tri-substituted imidazoles with a range of p38α MAPK inhibitory activities. Our studies demonstrated that suitably designed analogues of SB203580 can also be inducers of cardiomyogenesis in hESCs and that cell growth is affected by changes in the imidazole structures.

Collagen-nanofiber hydrogel composites promote contact guidance of human lymphatic microvascular endothelial cells and directed capillary tube formation.

Collagen and fibronectin matrices are known to stimulate migration of microvascular endothelial cells and the process of tubulogenesis, but the physical, chemical, and topographical cues for directed vessel formation have yet to be determined. In this study, growth, migration, elongation, and tube formation of human lymphatic microvascular endothelial cells (LECs) were investigated on electrospun poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactic-co-D-lactic acid) (PLDL) nanofiber-coated substrates, and correlated with fiber density and diameter. Directed migration of LECs was observed in the presence of aligned nanofibers, whereas random fiber alignment slowed down migration and growth of LECs. Cell guidance was significantly enhanced in the presence of more hydrophobic PLDL polymer nanofibers compared to PLGA (10:90). Subsequent experiments with tube-forming assays reveal the ability of resorbable hydrophobic nanofibers >300 nm in diameter to promote cell guidance in collagen gels without direct cell-fiber contact, in contrast to the previously reported contact-guidance phenomena. Our results show that endothelial cell guidance is possible within nanofiber/collagen-gel constructs that mimic the native extracellular matrix in terms of size and orientation of fibrillar components.

Cellular trans-differentiation and morphogenesis toward the lymphatic lineage in regenerative medicine.

Lymphedema is a medically irresolvable condition. The lack of therapies addressing lymphatic vessel dysfunction suggests that improved understanding of lymphatic cell differentiation and vessel maturation processes is key to the development of novel, regenerative medicine, and tissue engineering approaches. In this review we provide an overview of lymphatic characterization markers and morphology in development. Further, we describe multiple differentiation processes of the lymphatic system during embryonic, postnatal, and pathogenic development. Using the example of pathogenic Kaposi's sarcoma-associated herpes infection, we illustrate the involvement of the Notch and PI3K pathways for lymphatic transdifferentiation. We also discuss the plasticity of certain cell types and biofactors that enable transdifferentiation toward the lymphatic lineage. Here we argue the importance of pathway-associated induction factors for lymphatic transdifferentiation, including growth factors such as vascular endothelial growth factor receptor-C and interleukins, and the involvement of extracellular matrix characteristics and dynamics for morphological functionality.

The dose effect of human bone marrow-derived mesenchymal stem cells on epidermal development in organotypic co-culture.

BACKGROUND: A wealth of evidences have shown the participation and benefits of bone marrow-derived mesenchymal stem cells (BM-MSCs) in wound healing and skin tissue repair in vivo. However, their role in epidermal development and reconstitution is not clearly investigated. OBJECTIVE: Here we examine the quantitative effect of human BM-MSCs on epidermal regeneration in vitro. METHOD: Human keratinocytes and BM-MSCs are cultured at ratios from 0% to 100% on top of a fibroblast-embedded collagen gel in a three-dimensional organotypic co-culture model at an air-liquid interface up to 20 days and analyzed by histochemical and immunochemical staining of filaggrin, involucrin and keratin 10 on days 14 and 20. Human BM-MSCs were tracked with quantum dots in organotypic co-cultures. RESULTS: It was found that epidermal development is strongly influenced by the percentage of co-cultured BM-MSCs. A strong chemotactic effect between keratinocytes and MSCs was seen in the group with 50% of BM-MSCs, which resulted in an impaired epidermal development, whereas at a low percentage of BM-MSCs (10%), a stratified epidermal structure resembling native skin was established on day 14 of culture. Moreover, the immunostaining studies revealed that BM-MSCs in the low percentage (10%) participated in the basal periphery of reconstructed epidermis and a similar pattern characteristic of native epidermis was demonstrated in this experimental group, which was superior to all other experimental groups in terms of the thickness of stratum corneum and the expression profile of epidermal differentiation markers. CONCLUSION: This study indicates the advantage of using a new skin equivalent model incorporating a small fraction of MSCs to develop biologically useful tissues for maintaining homeostasis during skin regeneration and wound healing process.

Differentiation of bone marrow-derived mesenchymal stem cells into multi-layered epidermis-like cells in 3D organotypic coculture.

The interactions of bone marrow-derived mesenchymal stem cells (MSCs) and their engrafted microenvironment are an integral part of signaling control of stem cell lineage commitment. We attempted to induce bone marrow-derived MSCs to undergo epidermal lineage differentiation by manipulating the biochemical, environmental and physical properties of culture conditions in an organotypic coculture model to simulate a skin-specific microenvironment. The induction medium was optimized by varying different biomolecular supplements in a basic stratification medium. A multi-layered epidermis-like structure was established when MSCs were cultured in an optimized induction medium on a contractible fibroblast-embedded collagen gel with an air-liquid interface. The commitment into epidermal lineage was further confirmed by the expression of early and intermediate epidermalization markers - keratin 10 and filaggrin in 90.67% and 80.51% of MSCs, respectively. This study not only highlights the possibility of in vitro control of MSCs into epidermal lineage, but also suggests the therapeutic potential of bone marrow-derived MSCs for skin regeneration.