Prospective Isolation and Characterization of Chondroprogenitors from Human Chondrocytes Based on CD166/CD34/CD146 Surface Markers

An ultrastructural report of human articular cartilage resident cells in correlation with their phenotypic characteristics

The recent discovery of progenitors based on their differential fibronectin-adhesion (FAA-CPs) and migratory-based (MCPs) assay has evoked interest due to their superiority in terms of their efficient chondrogenesis and reduced hypertrophic propensity. This study aims to isolate and enrich three articular cartilage subsets, chondrocytes, FAA-CPs, and MCPs, and compare their undifferentiated and chondrogenic differentiated status, using in-vitro phenotypical characterization in correlation with ultrastructural analysis using Transmission Electron Microscopy (TEM). Following informed consent, cartilage shavings were procured from a non-diseased human ankle joint and cultured to obtain the three subsets. Chondrocytes exhibited higher CD106 and lower CD49b and CD146 levels. Following chondrogenic differentiation, corroborative results were seen, with the MCP group showing the highest GAG/DNA ratio levels and uptake of extracellular matrix stain as compared to the FAA-CP group. TEM analysis of the chondrocytes revealed the presence of more autolytic cells with disintegrated cytoplasm and plasma membrane. The differentiated FAA-CPs and MCPs displayed higher collagen and rough endoplasmic reticulum. The results presented in this study provide novel information on the ultrastructural characteristics of cartilage resident cells, with the chondrocyte group displaying features of terminal differentiation. Both progenitor subtypes showed superiority in varied contexts, with greater collagen fibrils and greater GAG content in MCPs. The display of preferential and differentiation traits sheds insight on the necessity to enrich progenitors and coculturing them with the general pool of constituent cells to combine their advantages and reduce their drawbacks to achieve a regenerative tissue displaying genuine hyaline-like repair while limiting their terminal differentiation.

CD146-positive adipose-derived stem cells subpopulation enriched by albumin magnetic sphere ameliorates knee osteoarthritis pain and promotes cartilage repair

BACKGROUND

The use of adipose stem cell (ADSCs) subpopulations in cartilage repair remains poorly characterized. In this study, we constructed an albumin magnetic sphere with specific targeting of CD146 (CD146-AMs) for sorting a subpopulation of CD146-positive ADSCs (CD146 + ADSCs) and explored the role of CD146 + ADSCs on joint pain and cartilage repair in rats with knee osteoarthritis (KOA).

METHODS

CD146-AMs were prepared and analyzed in materialistic characterization tests. Subpopulations of CD146 + ADSCs were sorted using CD146-AMs. Surface labeling, viability, and proliferation of a subpopulation of CD146 + ADSCs were evaluated in vitro. Molecular characterization of mRNA and protein expression profiles was analyzed by microarray. A rat KOA pain model was established by the iodoacetic acid method, and KOA pain and the promotion of cartilage repair were assessed after treatment with bilateral joint cavity injections of CD146 + ADSCs.

RESULTS

The CD146-AMs prepared in this study had an average particle size of 242.63 ± 6.74 nm, an average potential of 33.82 ± 3.53 mv, and high CD146 targeting and low cytotoxicity. The positive rate of enriched CD146 + ADSCs was 98.21% and showed a high level of stem cell marker expression and good cell viability. Gene and protein expression profiles showed that CD146 + ADSCs have different cellular functions, especially in regulating inflammation. In the KOA model, low, medium and high concentrations of CD146 + ADSCs were able to improve KOA pain and promote cartilage repair in a concentration-dependent trend.

CONCLUSIONS

The CD146-AMs prepared in this study were able to safely and efficiently sort out the CD146 + ADSCs subpopulation. The subpopulation of CD146 + ADSCs has a unique molecular profile that ameliorates KOA pain and repairs cartilage damage in rats, providing a new idea for KOA treatment.

The Upscale Manufacture of Chondrocytes for Allogeneic Cartilage Therapies

Allogeneic chondrocyte therapies need to be developed to allow more individuals to be treated with a cell therapy for cartilage repair and to reduce the burden and cost of the current two-stage autologous procedures. Upscale manufacture of chondrocytes using a bioreactor could help provide an off-the-shelf allogeneic chondrocyte therapy with many doses being produced in a single manufacturing run. In this study, we assess a good manufacturing practice-compliant hollow-fiber bioreactor (Quantum®) for adult chondrocyte manufacture. Chondrocytes were isolated from knee arthroplasty-derived cartilage (n = 5) and expanded in media supplemented with 10% fetal bovine serum (FBS) or 5% human platelet lysate (hPL) on tissue culture plastic (TCP) for a single passage. hPL-supplemented cultures were then expanded in the Quantum bioreactor for a further passage. Matched, parallel cultures in hPL or FBS were maintained on TCP. Chondrocytes from all culture conditions were characterized in terms of growth kinetics, morphology, immunoprofile, chondrogenic potential (chondrocyte pellet assays), and single telomere length analysis. Quantum expansion of chondrocytes resulted in 86.4 ± 38.5 × 106 cells in 8.4 ± 1.5 days, following seeding of 10.2 ± 3.6 × 106 cells. This related to 3.0 ± 1.0 population doublings in the Quantum bioreactor, compared with 2.1 ± 0.6 and 1.3 ± 1.0 on TCP in hPL- and FBS-supplemented media, respectively. Quantum- and TCP-expanded cultures retained equivalent chondropotency and mesenchymal stromal cell marker immunoprofiles, with only the integrin marker, CD49a, decreasing following Quantum expansion. Quantum-expanded chondrocytes demonstrated equivalent chondrogenic potential (as assessed by ability to form and maintain chondrogenic pellets) with matched hPL TCP populations. hPL manufacture, however, led to reduced chondrogenic potential and increased cell surface positivity of integrins CD49b, CD49c, and CD51/61 compared with FBS cultures. Quantum expansion of chondrocytes did not result in shortened 17p telomere length when compared with matched TCP cultures. This study demonstrates that large numbers of adult chondrocytes can be manufactured in the Quantum hollow-fiber bioreactor. This rapid, upscale expansion does not alter chondrocyte phenotype when compared with matched TCP expansion. Therefore, the Quantum provides an attractive method of manufacturing chondrocytes for clinical use. Media supplementation with hPL for chondrocyte expansion may, however, be unfavorable in terms of retaining chondrogenic capacity.

Gene Expression and Chondrogenic Potential of Cartilage Cells: Osteoarthritis Grade Differences

Recent data suggest that cells isolated from osteoarthritic (OA) cartilage express mesenchymal progenitor cell (MPC) markers that have the capacity to form hyaline-like cartilage tissue. Whether or not these cells are influenced by the severity of OA remains unexplored. Therefore, we analyzed MPC marker expression and chondrogenetic potential of cells from mild, moderate and severe OA tissue. Human osteoarthritic tibial plateaus were obtained from 25 patients undergoing total knee replacement. Each sample was classified as mild, moderate or severe OA according to OARSI scoring. mRNA expression levels of MPC markers—CD105, CD166, Notch 1, Sox9; mature chondrocyte markers—Aggrecan (Acan), Col II A1, hypertrophic chondrocyte and osteoarthritis-related markers—Col I A1, MMP-13 and ALPL were measured at the tissue level (day 0), after 2 weeks of in vitro expansion (day 14) and following chondrogenic in vitro re-differentiation (day 35). Pellet matrix composition after in vitro chondrogenesis of different OA-derived cells was tested for proteoglycans, collagen II and I by safranin O and immunofluorescence staining. Multiple MPC markers were found in OA cartilage resident tissue within a single OA joint with no significant difference between grades except for Notch1, which was higher in severe OA tissues. Expression levels of CD105 and Notch 1 were comparable between OA cartilage-derived cells of different disease grades and bone marrow mesenchymal stem cell (BM-MSC) line (healthy control). However, the MPC marker Sox 9 was conserved after in vitro expansion and significantly higher in OA cartilage-derived cells compared to its levels in the BM-MSC. The in vitro expansion of cartilage-derived cells resulted in enrichment while re–differentiation in reduction of MPC markers for all three analyzed grades. However, only moderate OA-derived cells after the in vitro chondrogenesis resulted in the formation of hyaline cartilage-like tissue. The latter tissue samples were also highly positive for collagen II and proteoglycans with no expression of osteoarthritis-related markers (collagen I, ALPL and MMP13). MPC marker expression did not differ between OA grades at the tissue level. Interestingly after in vitro re-differentiation, only moderate OA-derived cells showed the capacity to form hyaline cartilage-like tissue. These findings may have implications for clinical practice to understand the intrinsic repair capacity of articular cartilage in OA tissues and raises the possibility of these progenitor cells as a candidate for articular cartilage repair.

Silicon-Gold Nanoparticles Affect Wharton's Jelly Phenotype and Secretome during Tri-Lineage Differentiation

Multiple studies have demonstrated that various nanoparticles (NPs) stimulate osteogenic differentiation of mesenchymal stem cells (MSCs) and inhibit adipogenic ones. The mechanisms of these effects are not determined. The aim of this paper was to estimate Wharton’s Jelly MSCs phenotype and humoral factor production during tri-lineage differentiation per se and in the presence of silicon–gold NPs. Silicon (SiNPs), gold (AuNPs), and 10% Au-doped Si nanoparticles (SiAuNPs) were synthesized by laser ablation, characterized, and studied in MSC cultures before and during differentiation. Humoral factor production (n = 41) was analyzed by Luminex technology. NPs were nontoxic, did not induce ROS production, and stimulated G-CSF, GM-CSF, VEGF, CXCL1 (GRO) production in four day MSC cultures. During MSC differentiation, all NPs stimulated CD13 and CD90 expression in osteogenic cultures. MSC differentiation resulted in a decrease in multiple humoral factor production to day 14 of incubation. NPs did not significantly affect the production in chondrogenic cultures and stimulated it in both osteogenic and adipogenic ones. The major difference in the protein production between osteogenic and adipogenic MSC cultures in the presence of NPs was VEGF level, which was unaffected in osteogenic cells and 4–9 times increased in adipogenic ones. The effects of NPs decreased in a row AuNPs > SiAuNPs > SiNPs. Taken collectively, high expression of CD13 and CD90 by MSCs and critical level of VEGF production can, at least, partially explain the stimulatory effect of NPs on MSC osteogenic differentiation.