Advances and Challenges in Serum-Free Culture Systems for Mesenchymal Stem Cells: Toward Clinical-Grade Expansion

Mesenchymal stem cells (MSCs) are advancing rapidly towards clinical translation based on their immunomodulatory and regenerative potential. However, fetal bovine serum (FBS) dependence is still compromising safety, reproducibility, and regulatory clearance. To overcome this, serum-free and xeno-free platforms such as human platelet lysate, recombinant proteins, and chemically defined media (CDM) are strong contenders as alternatives. These media are a step up in safety, minimizing variability, and in compliance with good manufacturing practice (GMP); there are still some issues though. Costliness of recombinant supplements, donor variation in human-source additives, and lack of standardized potency assays are roadblocks in large-scale adoption. New advancements in bioreactors, omics-directed quality control, and artificial intelligence–regulated optimization hold promise for crossing roadblocks. This review is a compilation of state-of-the-art developments, critical analysis of translational roadblocks ahead, and a blueprint for making MSC expansion in serum-free settings scalable, economical, and clinically compliant. HIGHLIGHTS Provides a comprehensive review of serum-free, xeno-free, and chemically defined media for mesenchymal stem cell expansion, with emphasis on translational and regulatory challenges. Summarizes the advantages and limitations of human-derived supplements, recombinant proteins, and synthetic components, highlighting their roles in replacing fetal bovine serum. Discusses commercial serum-free/xeno-free products, comparing cost-effectiveness, GMP compliance, and clinical applicability. GRAPHICAL ABSTRACT