Introduction: Dynamic culturing systems can overcome challenges of in-vitro fabrication and maintenance of complex 3D tissues, however, the unique physiological conditions to which each tissue is subjected has been hampering noteworthy developments for many engineered tissues. Here we report the in-house development (design, manufacturing, and validation) of a glass slide size microbioreactor for the preparation, maintenance, and/or conditioning of human multilayer tissues or multi-tissue structures, evidencing applications in skin tissue-engineered analogs and ex-vivo human skin.
Methodology: The autoclavable bioreactor comprises a sandwich modular structure of hard undeformable layers of 3D printed medical grade polycarbonate intercalated with soft deformable layers of silicone. When compressed, the soft layers expand laterally against the sample sealing the layers between fluid streams avoiding their intermixing . The bioreactor is modular, each module being an independent fluid circuit for one tissue, and up to three modules can be assembled to enable multi-tissue structures cultured in dynamic conditions. Each fluid stream is regulated by an independent piezoelectric pressure controller coupled with a flow sensor that allow measuring the dispensed media.
Results: The bioreactor was capable of holding skin tissue samples of 8mm in diameter and of providing, without mixing, different culture media corresponding to the three layers of the tissue, the outmost epidermis, the underneath dermis, and the innermost adipose tissue. By changing the thickness of the soft layers, it could easily be adapted to accommodate samples from different anatomical regions and with varied thicknesses. The bioreactor allowed nourishing each cell type/tissue layer with a specific cell culture medium, increasing the maintenance time of the native structure in the ex-vivo skin. Furthermore, the bioreactor permits establishing an air-liquid interface for epidermis turnover in the skin explant, while still maintaining the separation of the culture media underneath.
Conclusions: This dynamic culture system contributes to diminishing the time of preparation of complex tissues or multi-tissues and prolonging the viability and use of in vitro and ex-vivo tissues being, therefore, a valuable tool for drug discovery, personalized medicine, and cancer development studies.
Acknowledgments: Consolidator Grant Project “ECM_INK” (ERC-2016-COG-726061).
1] L. Gasperini et al., “Bioreactor for tissue engineering of multi-tissue structure and manufacturing method,” Provisional Patent Application 116901, (2020).