A 3D bioprinted <i>in vitro</i> full-thickness skin aging model

Aging is caused by numerous factors resulting in physiological modification, affecting skin functionality. Developing an <i>in vitro</i> aging skin model is difficult since aging is a complex and cumulative activity throughout a person's lifetime. Moreover, skin is composed of multiple cell types; hence, it is challenging to replicate this intricate phenomenon quickly. Here, we report the development of a 3D bioprinted skin aging model using silk fibroin-gelatin bioink recapitulating the dual layer of the epidermis and dermis, along with a focus on the dermal-epidermal junction present in the native aged skin. We exploited the use of the senescent/late passage fibroblasts and keratinocytes in co-culture. This was compared with the proliferative/early passage cells as a control. Reduced fibronectin expression in gene and protein analysis, accompanied by a decline in collagen I, II, and IV expression, demonstrates the potency of our model in recapitulating the attributes of extrinsic aging <i>in vitro</i>. In addition, we created two diseased conditions - oxidative stress brought on by H₂O₂ and elevated glucose, as potential substitute agents for senescence induction. While both conditions were effective as alternate methods of inducing aging, high glucose was found to have more potency. Our developed 3D bioprinted skin aging model has numerous uses in basic research on aging, disease modeling, and screening of pharmaceutical active ingredients.