A simplified fabrication technique for cellularized high-collagen dermal equivalents

Abstract

Human autologous bioengineered skin has been successfully developed and used to treat skin injuries in a growing number of cases. In current clinical studies, the biomaterial used is fabricated via plastic compression of collagen hydrogel to increase the density and stability of the tissue. To further facilitate clinical adoption of bioengineered skin, the fabrication technique needs to be improved in terms of standardization and automation. Here, we present a one-step mixing technique using highly concentrated collagen and human fibroblasts to simplify fabrication of stable dermal equivalents. As controls, we prepared cellularized dermal equivalents with three varying collagen compositions. We found that the dermal equivalents produced using the simplified mixing technique were stable and pliable, showed viable fibroblast distribution throughout the tissue, and were comparable to highly concentrated manually produced collagen gels. Because no subsequent plastic compression of collagen is required in the simplified mixing technique, the fabrication steps and production time for dermal equivalents are consistently reduced. The present study provides a basis for further investigations to optimize the technique, which has significant promise in enabling efficient clinical production of bioengineered skin in the future.

Bioengineered Skin Intended for Skin Disease Modeling

“…The simplicity of the user interface and of the operation principle allows the injection by non-specialized staff [43,45]. The main disadvantage of the process is that the prior preparation of cells and biomaterials, as well as the in vitro cultivation remain manual and tedious [43,44]. Nevertheless, it is a promising method for the fabrication of consistent skin substitutes in an automatic, cost-efficient, and non-complex way.…”

“…Automated injection molding is another approach, developed and followed by the Product Development Group, Zurich [43,44]. It is based on the plastic compression method of Brazilius et al [14] but it employs a different technique for avoiding the high contraction of the formed collagen hydrogels.…”

“…It is based on the plastic compression method of Brazilius et al [14] but it employs a different technique for avoiding the high contraction of the formed collagen hydrogels. Fibroblasts suspension and high-concentration collagen, instead of low-concentration collagen [14], are mixed and injected into closed molds of 1mm thickness, while cultivation and incubation inside these molds follow to avoid contraction and maintain the size and shape of the dermal hydrogels (Figure 6) [44,45]. A skin-producing machine is used for the automatic blending and injection of the dermal components into the molds, which is considerably faster than manual plastic compression process [43,45].…”