Modulation of human iPSC-derived hepatocyte phenotype via extracellular matrix microarrays.

In vitro human liver models are essential for drug screening, disease modeling, and cell-based therapies. Induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHeps) mitigate sourcing limitations of primary human hepatocytes (PHHs) and enable precision medicine; however, current protocols yield iHeps with very low differentiated functions. The composition and stiffness of liver's extracellular matrix (ECM) cooperatively regulate hepatic phenotype in vivo, but such effects on iHeps remain unelucidated. Here, we utilized ECM microarrays and high content imaging to assess human iHep attachment and functions on ten major liver ECM proteins in single and two-way combinations robotically spotted onto polyacrylamide gels of liver-like stiffnesses; microarray findings were validated using hydrogel-conjugated multiwell plates. Collagen-IV supported higher iHep attachment than collagen-I over 2 weeks on 1 kPa, while laminin and its combinations with collagen-III, fibronectin, tenascin C, or hyaluronic acid led to both high iHep attachment and differentiated functions; laminin and its combination with tenascin or fibronectin led to similar albumin expression in iHeps and PHHs. Additionally, several collagen-IV-, laminin-, fibronectin-, and collagen-V-containing combinations on 1 kPa led to similar or higher CYP3A4 staining in iHeps than PHHs. Lastly, collagen-I or -III mixed with laminin, collagen-IV mixed with lumican, and collagen-V mixed with fibronectin led to high and stable functional output (albumin/urea secretions; CYP1A2/2C9/3A4 activities) in iHep cultures versus declining PHH numbers/functions for 3 weeks within multiwell plates containing 1 kPa hydrogels. Ultimately, these platforms can help elucidate ECM's role in liver diseases and serve as building blocks of engineered tissues for applications. STATEMENT OF SIGNIFICANCE: We utilized high-throughput extracellular matrix (ECM) microarrays and high content imaging to assess the attachment and differentiated functions of iPSC-derived human hepatocyte-like cells (iHep) on major liver ECM protein combinations spotted onto polyacrylamide gels of liver-like stiffnesses. We observed that iHep responses are regulated in unexpected ways via the cooperation between ECM stiffness and protein composition. Using this approach, we induced mature functions in iHeps on substrates of physiological stiffness and select ECM coatings at higher levels over 3+ weeks than analogous primary human hepatocyte cultures, which is useful for building platforms for drug screening, disease modeling, and regenerative medicine.