Development of cell supported injectable silk fibroin microcarriers for repair of damaged spinal cord

According to the data of the World Health Organization (WHO), spinal cord injuries affect between 250,000 and 500,000 people every year. In current clinical practice, there is no treatment method that can completely repair spinal cord injuries. There are barriers to cell-based regeneration approaches, such as low viability rates after transplantation of cells into the damaged spinal cord. The aim of this study is to develop an injectable microcarrier-assisted cell delivery system for the therapy of spinal cord injuries. Biodegradable microcarriers based on silk fibroin (SF), a natural protein, were prepared using the emulsified phase separation method. Microcarriers with 7 different silk fibroin concentrations at 1.5-6.5% weight/volume ratios were produced. As the silk fibroin concentration increased, the diameter of the microcarriers increased from 160.8±34.9 μm to 385.5±112.9 μm. It has been shown that the topographic properties of microcarriers can be changed by silk concentration, freezing temperature, and mixing speed. Particle diameter is directly related to injectability in microcarrier systems. Considering the suitable surface topography on which cells can proliferate, the microcarrier group (2.5 SF) with 2.5% silk fibroin concentration came to the fore among the 7 groups. The stabilization of the produced microcarriers was tested in two different alcohol solutions, methanol and ethanol. The developed microcarriers were characterized on the basis of their physical and chemical properties. At the end of study, in-vitro static and dynamic cell culture studies in 7 days were performed. Microcarriers provided mechanical support to L929 fibroblasts, MC3T3-E1 pre-osteoblasts and Schwann cells, ensuring that the viability of the cells increased even after they were injected. This research describes the first report of three dimensional microcarrier surfaces to examine Schwann cell proliferation. Cell-loaded injectability and biodegradability of spherical SF microcarriers provide a non-invasive treatment option. Thus supports the originality of the idea in the study.