Protocol for a Pilot Phase IIa Randomized, Placebo-Controlled, Double-Blind, Crossover Study of Umbilical Cord-Derived Mesenchymal Stem Cells (UCMSC) for the Treatment of Relapsing-Remitting Multiple Sclerosis (RRMS):The MSCell Study. PPCR 2024, 10 (3). https://doi.org/10.21801/ppcrj.2024.103.4.