Bioprinted autologous human skin equivalents for in vitro testing of therapeutic antibodies

In recent years, advances in tissue engineering have brought forward the accessibility of human skin equivalents for in vitro applications; however, the availability of human-based engineered tissue models suitable for high-throughput screening of biologics remains limited. Here, we report a method of manufacturing fully autologous (with both fibroblasts and keratinocytes from the same donor) human skin equivalents for determining preclinical therapeutic antibody adverse immune reactions in vitro. Using a combination of precise solenoid microvalve-based bioprinting and 96-well scale Alvetex inserts, autologous skin cells were bioprinted and cultured to develop a scalable approach to manufacturing skin equivalents. We demonstrated that fibroblasts and keratinocytes can be bioprinted with a high degree of precision while maintaining viability post printing. Histological staining showed that the bioprinted 96-well based skin equivalents were comparable to human skin. The fully autologous human skin equivalents were co-cultured in vitro with autologous peripheral blood monocytes with and without muromonab-CD3 (OKT3) and natalizumab (Tysabri), biologics which are known to cause and inhibit adverse immune reactions (type IV hypersensitivity), respectively. Analysis of supernatants from skin-equivalent monocyte co-cultures revealed significant proinflammatory cytokine responses (such as interferon gamma) in co-cultures treated with OKT3 when compared to Tysabri and negative controls. Consequently, this study provides proof of concept that through a combination of bioprinting and Alvetex scaffold-based culture systems, scalable human skin equivalents can be manufactured for high-throughput identification of adverse immune reactions during preclinical stages of the drug development process.