Paper BI-MoA11
Combinatorial Development of Biomaterials for Pluripotent Human Stem Cell Culture

Monday, October 29, 2012, 5:20 pm, Room 23

Pluripotent human stem cells include human embryonic stem cells (hESCs) and more recently developed human induced pluripotent stem cells (hIPSCs). These cells can replicate indefinitely in culture and can differentiate into all types of cells in human body. Thus, they hold remarkable promise as cell source for regenerative medicine and tissue engineering applications. However, hESCs and hIPSCs are currently cultured on a feeder cell layer of mitotically inactivated mouse embryonic fibroblasts (mEFs) or Matrigel^TM,extracellular matrix (ECM) protein mixtures secreted by mouse carcinoma cells. The utilization of mouse feeder cells and Matrigels as substrates leads to cell populations unsuitable for replacement therapy.

To address the challenge, we recently developed a high throughput polymer microarray technology to rapidly synthesize and test thousands of microscale substrates for hESC and hIPSC culture. In this study, 22 acrylate monomers were used to construct polymer arrays containing 496 different materials with diversified properties. Material properties including surface wettability, indentation elastic modulus, surface roughness and surface chemistry of each polymeric substrate in the array were quantified using high throughput methods. The results were then used to establish structure-function relationships between material properties and biological performance. Surface chemistry was shown to have controlling effects on hES cell undifferentiated growth while indentation elastic modulus or roughness had less pronounced effects on growth. The optimal (“hit”) surface was defined as certain oxygen containing ions and hydrocarbon ions in time of flight secondary ion mass spectrometry [ToF-SIMS] analysis. The “hit” surfaces can effectively enhance adsorption of vitronectin and engagement with integrin a_vb₃ and a_vb₅ to promote self-renewal of hESCs and hIPSCs.

Based on the structure-function relationship, favorable substrates for hESC and hIPSC culture was developed by exposing polystyrene (PS), a typical cell culture plastic, to an optimized dose of short wavelength ultraviolet ( UV ) light. In this way, key chemical moieties supporting self-renewal of hESCs and hIPSCs (e.g. hydrocarbons and ester/carboxylic acid) can be introduced onto the surface of PS. PS surfaces treated with the optimal dose of UV (i.e. UVPS) can support more than three times more cells per area than traditional mouse embryonic fibroblast (mEF) feeder cells, the current gold standard. As “hit” polymers, UVPS can promote adsorption of vitronectin to support self-renewal of hESCs and hIPSCs.