Optimized Alginate-Chitosan Coated Gelatin Microcarriers for Stem Cell Expansion in Regenerative Medicine

Background: Mesenchymal stem cells (MSCs) are promising for regenerative medicine due to their ability to self-renew, differentiate into multiple lineages, and modulate immune responses. However, large-scale expansion is essential to meet clinical needs, which is limited by traditional 2D cultures that lack the complexity of the native 3D environment. Microcarriers provide an efficient 3D alternative, enabling high-density cell growth in suspension systems. Natural polymers, such as alginate and chitosan, are ideal for microcarrier fabrication due to their biocompatibility and degradability. Coating them with gelatin can further enhance cell adhesion and functionality. Methods: In this study, microcarriers were fabricated from alginate and chitosan using ionic crosslinking—sodium tripolyphosphate (TPP) for chitosan and calcium chloride for alginate. Both types of carriers were subsequently coated with 1% gelatin and stabilized via crosslinking with glutaraldehyde. The fabricated microcarriers were thoroughly characterized using scanning electron microscopy (SEM) to observe morphology, Fourier-transform infrared spectroscopy (FT-IR) to confirm gelatin deposition, and differential scanning calorimetry (DSC) to assess thermal stability. Human MSCs were cultured on the microcarriers, and cell proliferation was evaluated using the MTT assay. Immunofluorescence staining was also performed to assess cytoskeletal organization and cellular attachment. Results: SEM analysis revealed smoother surface morphology and reduced roughness following gelatin coating, promoting better cell interaction. FT-IR spectra confirmed the presence of gelatin functional groups on both types of microcarriers, verifying successful coating. DSC analysis demonstrated improved thermal stability post-gelatin deposition. The MTT assay showed significantly higher MSC viability and proliferation on alginate-gelatin (AL/G) microcarriers compared to both chitosan-based and uncoated controls (p < 0.05). Furthermore, immunofluorescence staining indicated enhanced cytoskeletal organization and more extensive cell spreading on AL/G carriers, supporting their superior biocompatibility. Conclusion: Gelatin-coated alginate microcarriers demonstrated superior physicochemical properties and biocompatibility, making them ideal candidates for MSC expansion in regenerative medicine applications.