Novel nano-microspheres containing chitosan, hyaluronic acid, and chondroitin sulfate deliver growth and differentiation factor-5 plasmid for osteoarthritis gene therapy / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

OBJECTIVE@#To construct a novel non-viral vector loaded with growth and differentiation factor-5 (GDF-5) plasmid using chitosan, hyaluronic acid, and chondroitin sulfate for osteoarthritis (OA) gene therapy.@*METHODS@#Nano-microspheres (NMPs) were prepared by mixing chitosan, hyaluronic acid, and chondroitin sulfate. GDF-5 plasmid was encapsulated in the NMPs through electrostatic adsorption. The basic characteristics of the NMPs were observed, and then they were co-cultured with chondrocytes to observe their effects on extracellular matrix (ECM) protein expression. Finally, NMPs loaded with GDF-5 were injected into the articular cavities of rabbits to observe their therapeutic effects on OA in vivo.@*RESULTS@#NMPs exhibited good physicochemical properties and low cytotoxicity. Their average diameter was (0.61±0.20) μm, and encapsulation efficiency was (38.19±0.36)%. According to Cell Counting Kit-8 (CCK-8) assay, relative cell viability was 75%-99% when the total weight of NMPs was less than 560 μg. Transfection efficiency was (62.0±2.1)% in a liposome group, and (60.0±1.8)% in the NMP group. There was no significant difference between the two groups (P>0.05). Immunohistochemical staining results suggested that NMPs can successfully transfect chondrocytes and stimulate ECM protein expression in vitro. Compared with the control groups, the NMP group significantly promoted the expression of chondrocyte ECM in vivo (P<0.05), as shown by analysis of the biochemical composition of chondrocyte ECM. When NMPs were injected into OA model rabbits, the expression of ECM proteins in chondrocytes was significantly promoted and the progression of OA was slowed down.@*CONCLUSIONS@#Based on these data, we think that these NMPs with excellent physicochemical and biological properties could be promising non-viral vectors for OA gene therapy.

MicroRNA-21 controls the development of osteoarthritis by targeting GDF-5 in chondrocytes

Osteoarthritis is a common cause of functional deterioration in older adults and is an immense burden on the aging population. Altered chondrogenesis is the most important pathophysiological process involved in the development of osteoarthritis. However, the molecular mechanism underlying the regulation of chondrogenesis in patients with osteoarthritis requires further elucidation, particularly with respect to the role of microRNAs. MiR-21 expression in cartilage specimens was examined in 10 patients with knee osteoarthritis and 10 traumatic amputees. The effect of miR-21 on chondrogenesis was also investigated in a chondrocyte cell line. The effect of miR-21 on the expression of growth differentiation factor 5 (GDF-5) was further assessed by luciferase reporter assay and western blot. We found that endogenous miR-21 is upregulated in osteoarthritis patients, and overexpression of miR-21 could attenuate the process of chondrogenesis. Furthermore, we identified GDF-5 as the direct target of miR-21 during the regulation of chondrogenesis. Our data suggest that miR-21 has an important role in the pathogenesis of osteoarthritis and is a potential therapeutic target.

Identification of a GDF5 Mutation in a Korean Patient with Brachydactyly Type C without Foot Involvement

Brachydactyly type C (BDC) is characterized by shortening of the middle phalanges of the index, middle, and little fingers. Hyperphalangy of the index and middle finger and shortening of the first metacarpal can also be observed. BDC is a rare genetic condition associated with the GDF5 gene, and this condition has not been confirmed by genetic analysis so far in the Korean population. Herein, we present a case of a 6-yr-old girl diagnosed with BDC confirmed by molecular genetic analysis. The patient presented with shortening of the second and third digits of both hands. Sequence analysis of the GDF5 gene was performed and the pathogenic mutation, c.1312C>T (p.Arg438Cys), was identified. Interestingly, this mutation was previously described in a patient who presented with the absence of the middle phalanges in the second through fifth toes. However, our patient showed no involvement of the feet. Considering intrafamilial and interfamilial variability, molecular analysis of isolated brachydactyly is warranted to elucidate the genetic origin and establish a diagnosis.