Mesenchymal Stem Cells (MSCs) in Targeted Drug Delivery: Literature Review and Exploratory Data on Migrating and Differentiation Capacities of Bone MSCs into Hepatic Progenitor Cells

Background and Objective: Mesenchymal stem cells (MSCs), particularly bone MSCs (BMSCs) offer great potentials for targeted therapeutic applications due to their migratory and differentiation capacities. Significant advances have been achieved in the differentiation of hepatocyte or hepatocyte-like cells both in vitro and in vivo. However, there is limited knowledge on the differentiation of BMSCs into bipotential hepatic progenitor cells or cholangiocytes. This study reviews the potentials and advances in using MSCs as vehicles for targeted drug delivery and proposes a new method for induction of differentiation in rat BMSCs into hepatic progenitor cells in vitro, and assesses the differential and migratory capacities. Methods: The BMSCs of Sprague Dawley (SD) rats were harvested from the femur and the tibiae of the rats. After isolation and culturing, BMSCs from Passage 1 were used for the study. The in vitro differentiation of the hepatic progenitor cells was performed using a 2-step induction approach after 5-day serum deprivation from the BMSCs and culturing in Dulbecco's modified eagle medium. Spontaneous in vitro differentiation of BMSCs was examined in the absence of growth factors for 15 days as a control treatment. Hepatocytes differentiation was achieved by exposing the culture to collagen type I-coated plates. Cholangiocytes differentiation was achieved by replating the BMC-HepPCs on a layer of Matrigel. Immunofluorescence was conducted on twelve-well plates to determine cell differentiation. Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) was used to determine the total RNA extracted using the Trizol LS reagent. In the hepatocyte differentiation group, after periodic acid-schiff (PAS) staining for glycogen, the inverted microscope was used to determine differentiation and undifferentiated BMC-HepPCs served as controls. The amount of low-density lipoprotein (LDL) uptake by the BMSCs-derived hepatocytes were assessed using fluorescence microscopy. The secretion of rat albumin was quantified using a quantitative ELISA kit. Results: Differentiation induction is indicative of the sequential supplementation of sodium butyrate and cytokines, which are involved in the embryonic development of the mammalian liver. Hepatic progenitor cells, derived from bone marrow, can be differentiated bidirectionally in vitro into both hepatocyte and cholangiocyte cell lines. The differentiated cells, including hepatic progenitor cells, hepatocytes, and bile duct-like cells, were identified and analyzed at mRNA and protein levels. Conclusion: Our findings show that BMSCs can be utilized as novel bipotential hepatic progenitor cells and thereby for hepatobiliary disease treatment or hepatobiliary tissue engineering.