HOW TO CULTURE HEMATOPOIETIC CELLS ON BIOLAMININ SUBSTRATES

Laminins play a major role in the hematopoietic microenvironment

Laminins are widely expressed in human bone marrow play a major role in the hematopoietic microenvironment. Laminin isoforms 521, 511, 411 and 421 are the most abundant, synthesized by human bone marrow stromal cells (Siler, 2000). Laminin 521 and laminin 511 have been shown to have the strong adhesive interaction with CD34+ human hematopoietic stem cells (HSC) and progenitor cells, mediated largely via the integrin a6B1 receptor (Siler, 2000; Qian, 2006). Laminin 521 and laminin 511 is also highly adhesive to lineage-committed myelomonocytic and erythroid progenitor cells and most lymphoid and myeloid cell lines (Gu, 2003). These alpha-5 containing laminins also stimulate migration and proliferation of human hematopoietic progenitor cells (Gu, 2003), suggesting a important physiological role of laminins during hematopoiesis. Other laminin isoforms, such as laminin 111, show only weak adhesive interaction (Siler, 2000; Gu, 2003). Rodent CD34+ HSC transplantation experiment has shown that the laminin-integrin interaction also mediates homing (Qian, 2006; Carvalho, 2008).

Biolaminin 521 is an optimal substrate for large-scale production of clinically compliant megakaryocytes and platelets

Due to the biorelevant environment created, Biolaminin 521 is an optimal substrate for clinically compliant hematopoietic differentiation. In a publication by Börger et al, the authors present a animal component-free and defined protocol for the generation of functional megakaryocytes and platelets from a HLA-universal iPSCs on the human recombinant Biolaminin 521 culture substrate (Börger, 2015). 
Biolaminin 521 has also succesfully been used for large-scale MK production. With an effective, xeno-free and scalable system, Biolaminin 521-coated microcarriers increased MK production per iPSC by up to 10-fold (18.7x10⁷ MKs per 50 ml medium). MKs obtained in this system showed typical features of mature MKs and were able to produce PLTs in vitro and in vivo (Eicke, 2018). Laminins also has an important contribution to thrombus formation in vivo. Schaff and colleagues (2013) show that laminin 411, laminin 511, and laminin 521, but not laminin 211, allow efficient platelet adhesion and activation (via integrin a6B1) across a wide range of arterial wall shear rates.

iPS cell derived megakaryocyte with proplatelets.
Courtesy of Dorothee Eicke, Hannover Med. School.

A recent publication by Singapore researchers (Sivalingam, 2016) show that a Biolaminin 521 coated microcarrier-based embryoid body (EB) platform support superior red blood cell (RBS) generation from human pluripotent stem cells. The authors developed a scalable, serum- and animal component-free, and chemically defined microcarrier-based platform using human recombinant Biolaminin 521 as an extracellular matrix for hPSC expansion, EB formation, and subsequently hematopoietic differentiation of hPSC. Improved survival and better quality EBs generated with the microcarrier-based method resulted in significantly improved mesoderm induction and resulted in drastic improvement in hematopoietic precursor expansion and the yield of RBS generation compared to a conventional EB-based differentiation method.