Few methods are available to regenerate articular cartilage defects in patients with osteoarthritis. We aimed to assess the safety and efficacy of articular cartilage regeneration by a novel medicinal product composed of allogeneic human umbilical cord blood‐derived mesenchymal stem cells (hUCB‐MSCs). Patients with Kellgren‐Lawrence grade 3 osteoarthritis and International Cartilage Repair Society (ICRS) grade 4 cartilage defects were enrolled in this clinical trial. The stem cell‐based medicinal product (a composite of culture‐expanded allogeneic hUCB‐MSCs and hyaluronic acid hydrogel [Cartistem]) was applied to the lesion site. Safety was assessed by the World Health Organization common toxicity criteria. The primary efficacy outcome was ICRS cartilage repair assessed by arthroscopy at 12 weeks. The secondary efficacy outcome was visual analog scale (VAS) score for pain on walking. During a 7‐year extended follow‐up, we evaluated safety, VAS score, International Knee Documentation Committee (IKDC) subjective score, magnetic resonance imaging (MRI) findings, and histological evaluations. Seven participants were enrolled. Maturing repair tissue was observed at the 12‐week arthroscopic evaluation. The VAS and IKDC scores were improved at 24 weeks. The improved clinical outcomes were stable over 7 years of follow‐up. The histological findings at 1 year showed hyaline‐like cartilage. MRI at 3 years showed persistence of the regenerated cartilage. Only five mild to moderate treatment‐emergent adverse events were observed. There were no cases of osteogenesis or tumorigenesis over 7 years. The application of this novel stem cell‐based medicinal product appears to be safe and effective for the regeneration of durable articular cartilage in osteoarthritic knees. Stem Cells Translational Medicine 2017;6:613–621

IntroductionThe present work was designed to explore the feasibility and efficacy of articular cartilage repair using composites of human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) and four different hydrogels in a rat model.MethodsFull-thickness articular cartilage defects were created at the trochlear groove of femur in both knees of rats. Composites of hUCB-MSCs and four different hydrogels (group A, 4% hyaluronic acid; group B, 3% alginate:30% pluronic (1:1, v/v); group C, 4% hyaluronic acid: 3% alginate: 20% pluronic (2:1:1, v/v}; and group D, 4% hyaluronic acid:3% alginate:20% pluronic;chitosan (4:1:1:2, v/v).) were then transplanted into right knee defect in each study group (five rats/group). Left knees were transplanted with corresponding hydrogels without hUCB-MSCs as controls. At 16 weeks post-transplantation, degrees of cartilage repair were evaluated macroscopically and histologically using Masson’s Trichrome, safranin-O, Sirius red staining, and type-II collagen immunostaining.ResultsOverall, group A with 4% hyaluronic acid hydrogel resulted in superior cartilage repair grossly and histologically and achieved a cellular arrangement and collagen organization pattern mimicking adjacent uninjured articular cartilage. Immunostaining and safranin-O staining also revealed that group A displayed the largest areas of type II collagen staining. Sirius red staining revealed that the organization pattern of collagen bundles was more similar to normal cartilage in group A. No evidence of rejection was found.ConclusionsThe results of this study suggest that hUCB-MSCs could be used to repair articular cartilage defects in vivo and that hyaluronic acid is an attractive hydrogel candidate for use in combination with hUCB-MSCs.

ABSTRACT:Genetic variants of three human organic cation transporter genes (hOCTs) were extensively explored in a Korean population. The functional changes of hOCT2 variants were evaluated in vitro, and those genetic polymorphisms of hOCTs were compared among different ethnic populations. From direct DNA sequencing, 7 of 13 coding variants were nonsynonymous single-nucleotide polymorphisms (SNPs), including four variants from hOCT1 (F160L, P283L, P341L, and M408V) and three from hOCT2 (T199I, T201M, and A270S), whereas 6 were synonymous SNPs. The linkage disequilibrium analysis presented for three independent LD blocks for each hOCT gene showed no significant linkage among all three hOCT genes. The transporter activities of MDCK cells that overexpress the hOCT2-T199I, -T201M, and -A270S variants showed significantly decreased uptake of showed a 2-to 5-fold increase in K m values and a 10-to 20-fold decrease in V max values. The allele frequencies of the five functional variants hOCT1-P283L, -P341L, and hOCT2-T199I, -T201M, and -A270S were 1.3, 17, 0.7, 0.7, and 11%, respectively, in a Korean population; the frequency distributions of these variants were not significantly different from those of Chinese and Vietnamese populations. These findings suggest that genetic variants of hOCTs are not linked among three genes in a Korean population, and several of the hOCT genetic variants cause decreased transport activity in vitro compared with the wild type, although the clinical relevance of these variants remains to be evaluated.The human organic cation transporters hOCT1, hOCT2, and hOCT3 mediate electrogenic transport of small organic cations with different molecular structures, independent of sodium gradient (Koepsell, 1999). These organic cation substrates include clinically important therapeutics (e.g., metformin, procainamide, and cimetidine), endogenous compounds (e.g., dopamine and norepinephrine), as well as toxic substances [e.g., tetraethylammonium bromide (TEA), HPP ϩ , and methyl-4-phenylpyridinium acetate (MPP ϩ )] (Gorboulev et al., 1997;Zhang et al., 1997;Kang et al., 2006). Although these transporters show extensive overlaps in their substrate specificities, they exhibit distinct differences in tissue distribution; hOCT1 is primarily found in the sinusoidal membrane of hepatocytes and, to a lesser extent, in intestinal epithelial cells, whereas hOCT2 is mainly expressed in the basolateral membrane of kidney proximal tubules, and hOCT3 shows a widespread tissue distribution that includes the brain, heart, and liver. Based on their properties and tissue distributions, hOCT1, hOCT2, and hOCT3 are thought to play important roles in the excretion and distribution of organic cations in the liver, kidney, and brain (Jonker and Schinkel, 2004).Knockout mouse models have been generated for the Oct1, Oct2, and Oct3 genes to elucidate the in vivo function of the OCT transporters. Oct1-, Oct2-, and Oct3-deficient mice are viable and display no obvious phenotypic abnormalities (Jonker et al., 2001Zwart et al., 2001...