Developing an Optimal Biofunctional Scaffold for Hematopoietic Stem Cell Quiescent Maintenance and Expansion

Hematopoietic stem cells (HSCs), characterized by their CD34 glycoprotein expression, can be extensively exploited in a variety of clinical applications to treat bone-marrow related disorders and cancers, which affect hundreds of thousands worldwide. HSCs are known to efficiently self-renew and maintain their quiescent state in their in vivo microenvironment, but rapidly lose their multipotency in vitro due to quick onsets of differentiation. Shortages of available donor cells have led to scientific interest in developing biofunctional scaffolds – such as cross-linked polymer hydrogels – that mimic the natural stem cell niche. Here we show that a firm, gelatin-based hydrogel cross-linked by microbial transglutaminase (mTG) (in a ratio of 1:25 mTG to gelatin) is ideal for quiescent self-renewal, and that the purine derivative, Stemregenin 1 (SR1), aids in directing cell migration, proliferation, and stemness. The 1:25 ratio with exposure to SR1 yielded a promisingly high stemness level of 94.53%. Our results demonstrate the previously undocumented effectiveness of gelatin hydrogels as biomimetic scaffolds suitable for HSC expansion. Furthermore, our findings and the culture system we have developed are expected to facilitate bone marrow disease treatment by providing large quantities of quiescent HSCs for medical applications and potentially diminishing the high demand for marrow donors.