Introduction: The use of human stem cells in regenerative medicine and drug screening is predicated on the ability to effectively direct both their undifferentiated expansion and differentiation into desired lineages. Exquisite control over stem cell fate is needed to efficiently produce sufficient, defined cell populations for such applications, yet this is substantially hindered by undefined culture components, signal crosstalk between multiple exogenous and endogenous factors, and spatiotemporal variations in microenvironmental composition inherent to conventional culture formats.
Experimental: We have developed scalable, valveless, continuous-flow microbioreactor arrays that both provide a full-factorial set of exogenous factor compositions, and also allow controlled accumulation of paracrine factors.
Results: Using pluripotency maintenance and mesendodermal differentiation of human pluripotent stem cells (hPSCs) as examples, we demonstrate the unique ability of this platform to separate, visualise (at both population level and single cell resolution), identify and modulate paracrine effects that are not otherwise readily accessible. In addition, we have applied this same technology platform to the optimization of maintenance (and improvement) of potency of human mesenchymal stem cells, and the impact of small molecule agonists and antagonists on osteogenic differentiation outcomes. Importantly, optimization of these culture conditions with the arrays was readily translatable to improving differentiation in conventional static culture protocols, exemplifying the immediate practicality of the microbioreactor array platform.
Conclusion: This multiplexed microbioreactor platform deciphers factor interplay and signalling hierarchies that control of stem cell fate, and is applicable as a universal microenvironmental screening platform for bioprocess optimisation, media formulation design, quality control for cellular therapeutics and cell-based drug toxicity and discovery.