Insulin-producing INS-1 cell cultures on biomimetic 3D scaffolds

Three-dimensional cell cultures on biomimetic scaffolds have gained significant attention in tissue engineering, drug delivery, and scalable cell production. Current challenges in creating an ideal scaffold are providing maximum space for cells to grow while ensuring efficient nutrient, metabolite, and gas exchange to prevent the formation of necrotic or apoptotic regions. In our work, we grow insulin-producing INS-1 cells on touch-spun polycaprolactone (PCL) fiber scaffolds. Touch-spinning allows the creation of finely aligned 3D mesh-like fiber scaffolds with controllable distance between the fibers, resulting in a minimum of abiotic scaffold material and providing maximum space for cells to grow. Adding Matrigel at different combinations allowed us to control the INS-1 proliferation profile and grow them either in the form of scarce large (up to 1 mm) spheroids (no Matrigel), numerous smaller (about 150-200 μm in diameter) spheroids (Matrigel added to the cells only) or cell sheets (Matrigel added to both cells and fibers). Growing INS-1 cells as nanofiber-reinforced cell sheets is of utmost importance because it opens the possibility of using them in cell sheet tissue engineering. Obtaining free-floating sheets of insulin-producing cells by traditional means is typically challenging due to their fragility. Being only about 4-6 cells thick, INS-1 cell sheets are not prone to forming necrotic cores, which is a common problem for all 3D spheroid cultures when they reach a diameter of more than 150-200 μm. At the same time, they preserved their insulin production ability and characteristics of 3D cultures, such as numerous cell-to-cell contacts and metabolic activity.