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To develop a soft-to-hard tissue interface, we made a decellularized dermis/poly(methyl methacrylate) (PMMA) complex by soaking the decellularized dermis in methyl methacrylate (MMA) and an initiator, and then polymerizing the MMA. The decellularized tissue was chosen because of its good biocompatibility and the easiness of suturing it, and MMA because of its hard tissue compatibility and wide use in the biomedical field. The MMA filled the cavities in the dermis and polymerized within 10 min. No leaking or polymer aggregation was observed, implying that a homogenous tissue-polymer complex had formed. The cell infiltration and the integration between the tissue and the dermis occurred in vivo, whereas the cells could not infiltrate the tissue-polymer complex. This implies that the interface tissue should possess both complex and noncomplex parts, where the cells infiltrate the noncomplex part and stop when they encounter the complex part, integrating the soft and hard tissue or hard polymer.

To develop a method for making percutaneous devices that have high biocompatibility and do not induce downgrowth of epidermal cells, we prepared a partial decellularized dermis (DD)/poly(methyl methacrylate) (PMMA) complex (PDPC) with a PMMA rod firmly stabilized inside. The porcine decellularized tissue was chosen because of its high biocompatibility and mechanical properties, and MMA was used because it would adhere firmly to a polymer such as a catheter. The MMA filled the cavities in the dermis and polymerized, anchoring to the collagenous fibrils inside the porcine DD. The PDPC was cemented to the PMMA rod tightly and it was integrated with the surrounding tissue within 12 weeks of implantation. Furthermore, no downgrowth of the epidermis, which may cause clinical problems, was observed. We consider that the tissue-polymer complex may be a suitable candidate for use in percutaneous devices.

Polymerization is a technique used to functionalize soft tissues and to produce interface tissues. Here, we developed a method for functionalizing soft tissue with diverse polymers, using in-situ polymerization of monomers that were absorbed into the tissue. Specifically, methyl methacrylate (MMA) and a photoinitiator (Irgacure® 184) were applied to the decellularized dermis, which was polymerized in-situ using irradiating ultraviolet light. MMA polymerization in-situ was possible because the monomers filled the cavities of the decellularized dermis. It took approximately 40 min to complete polymerization, but we found that the rate and depth of polymerization could be adjusted by using mixtures of Irgacure® 184 and Irgacure® 819. The addition of Irgacure® 819 increased polymerization, indicating that polymerization of MMA had occurred inside the dermis. Additionally, we showed that a complex of dermis and poly(methyl methacrylate) (PMMA) increase mechanical strength, which indicates that the PMMA is anchored to collagen fibers. This makes the complex very stable, giving it the functionality of both soft and hard tissue.

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