Organ-specific Expression Data Steer Choice of Laminin for In Vitro Studies in Biologically Relevant Drug Discovery and Development Platforms

Abstract: The Drug Discovery and Development (DDD) process incorporates multiple cell culture platforms to assess the safety and efficacy of lead compounds against a target for an indication. In recent years, with the advancement of stem cell research protocols, there has been shift in focus from 2D cell culture techniques to more complex patient-derived models. Human pluripotent stem cells (hPSCs) require an extracellular matrix (ECM) for maintenance, expansion, and differentiation; laminins, a large ECM protein family enriched within basement membranes of epithelial and endothelial tissues, are an essential part of the stem cell niches. While laminins are increasingly implemented in hPSC research, standardised protocols using biologically relevant ECM in DDD platforms have not been developed.

Thus, we assessed protein and gene expression patterns of laminin isoforms in four distinct tissues most commonly used in DDD: the heart, liver, kidney and central nervous system (in vivo), before translation to proliferation and expression experiments in specified cell-types on laminin substrates (in vitro). We found the expression pattern is largely tissue- and cell type specific, for example, in the kidney. We also show that providing the relevant laminin isoform in vitro leads to increased standardization and functionality. For example, when using laminin as a substrate in culture, 43-times more dopaminergic neurons and >80% functional cardiovascular progenitor cells (vs ?50% with competitor substrates), were observed. We also demonstrate how Biolaminins can be implicated in downstream microfluidic platforms to recreate the in vivo microenvironment when flow is introduced.

Taken together, we demonstrate tissue- and cell-specific expression of laminin isoforms. In vivo expression data can guide scientists to recapitulate the ECM microenvironment of a given cell or tissue to promote optimal in vitro conditions–an important consideration as we aim to create more biologically-relevant cell-based models to move away from animal models. By doing so, current limitations including differentiation, reproducibility, and maturity of PSC-derived cells can be addressed in more sophisticated DDD applications, such as organ-on-a-chip platforms.