Alginate-chitosan microencapsulated cells for improving cd34⁺ progenitor maintenance and expansion

Protocols for isolation, characterization, and transplantation of hematopoietic stem cells (HSCs) have been well established. However, difficulty in finding human leucocyte antigens (HLA)-matched donors and scarcity of HSCs are still the major obstacles of allogeneic transplanta-tion. In this study, we developed a double-layered microcapsule to deliver paracrine factors from non-matched or low-matched HSCs to other cells. The umbilical cord blood-derived hematopoietic progenitor cells, identified as CD34⁺ cells, were entrapped in alginate polymer and further protected by chitosan coating. The microcapsules showed no toxicity for surrounding CD34⁺ cells. When CD34⁺ cells-loaded microcapsules were co-cultured with bare CD34⁺ cells that have been collected from unrelated donors, the microcapsules affected surrounding cells and increased the percentage of CD34⁺ cell population. This study is the first to report the potency of alginate-chitosan microcap-sules containing non-HLA-matched cells for improving proliferation and progenitor maintenance of CD34⁺ cells.