Seiji Kubo

Blocking vascular endothelial growth factor with soluble Flt‐1 improves the chondrogenic potential of mouse skeletal muscle–derived stem cells

OBJECTIVE To investigate the effect of vascular endothelial growth factor (VEGF) stimulation and the effect of blocking VEGF with its antagonist, soluble Flt-1 (sFlt-1), on chondrogenesis, using muscle-derived stem cells (MDSCs) isolated from mouse skeletal muscle. METHODS The direct effect of VEGF on the in vitro chondrogenic ability of mouse MDSCs was tested using a pellet culture system, followed by real-time quantitative polymerase chain reaction (PCR) and histologic analyses. Next, the effect of VEGF on chondrogenesis within the synovial joint was tested, using genetically engineered MDSCs implanted into rat osteochondral defects. In this model, MDSCs transduced with a retroviral vector to express bone morphogenetic protein 4 (BMP-4) were coimplanted with MDSCs transduced to express either VEGF or sFlt-1 (a VEGF antagonist) to provide a gain- and loss-of-function experimental design. Histologic scoring was used to compare cartilage formation among the treatment groups. RESULTS Hyaline-like cartilage matrix production was observed in both VEGF-treated and VEGF-blocked (sFlt-1-treated) pellet cultures, but quantitative PCR revealed that sFlt-1 treatment improved the expression of chondrogenic genes in MDSCs that were stimulated to undergo chondrogenic differentiation with BMP-4 and transforming growth factor beta3 (TGFbeta3). In vivo testing of articular cartilage repair showed that VEGF-transduced MDSCs caused an arthritic change in the knee joint, and sFlt-1 improved the MDSC-mediated repair of articular cartilage, compared with BMP-4 alone. CONCLUSION Soluble Flt-1 gene therapy improved the BMP-4- and TGFbeta3-induced chondrogenic gene expression of MDSCs in vitro and improved the persistence of articular cartilage repair by preventing vascularization and bone invasion into the repaired articular cartilage.

The influence of sex on the chondrogenic potential of muscle-derived stem cells: Implications for cartilage regeneration and repair

OBJECTIVE To explore possible differences in muscle-derived stem cell (MDSC) chondrogenic differentiation in vitro and articular cartilage regeneration in vivo between murine male MDSCs (M-MDSCs) and female MDSCs (F-MDSCs). METHODS Three different populations of M- and F-MDSCs (n = 3 of each sex) obtained via preplate technique, which separates cells based on their variable adhesion characteristics, were compared for their in vitro chondrogenic potential using pellet culture. Cells were assayed with and without retroviral transduction to express bone morphogenetic protein 4 (BMP-4). The influence of both expression of stem cell marker Sca1 and in vitro expansion on the chondrogenic potential of M- and F-MDSCs was also determined. Additionally, BMP-4-transduced M- and F-MDSCs were applied to a full-thickness articular cartilage defect (n = 5 each) on the femur of a nude rat, and the quality of the repaired tissue was evaluated by macroscopic and histologic examination. RESULTS With and without BMP-4 gene transduction, M-MDSCs produced significantly larger pellets with a richer extracellular matrix, compared with F-MDSCs. Sca1 purification influenced the chondrogenic potential of MDSCs, especially M-MDSCs. Long-term culture did not affect the chondrogenic potential of M-MDSCs but did influence F-MDSCs. M-MDSCs repaired articular cartilage defects more effectively than did F-MDSCs at all time points tested, as assessed both macroscopically and histologically. CONCLUSION Our findings demonstrate that sex influences the chondrogenic differentiation and articular cartilage regeneration potential of MDSCs. Compared with female MDSCs, male MDSCs display more chondrogenic differentiation and better cartilage regeneration potential.

WISSENSCHAFTLICHER BEITRAG: Anatomical double bundle anterior cruciate ligament reconstruction using tibialis anterior tendon allografts: Reconstruction through two femoral and two tibial tunnels

Zusammenfassung Durch die Verbesserung der VKB-Rekonstruktion mit der Einzelbundel-(1-Kanal)-Technik konnten gute klinische Resultate erreicht werden. Trotzdem kann eine abnormale Rotationsinstabilitat nach Einzelbundel-VKB-Rekonstruktion bei guter antero-posteriorer Stabilitat auftreten und sollte vermieden werden, da eine fehlende Wiederherstellung der Rotationsstabilitat nach VKB-Rekonstruktion zu einer schlechten Kniefunktion und zur Unzufriedenheit der Patienten fuhren kann. In-vitro-biomechanische Studien zeigten, dass die anatomische 2-Bundel-(2-Kanal)- Technik zu signifikant weniger anteriorer Translation der Tibia und weniger Rotationsinstabilitat als die Einzelbundeltechnik fuhrt. Ebenfalls sind die Resultate der ersten klinischen Kurzzeitnachuntersuchungen positiv. Aufgrund dieser Tatsachen empfehlen wir eine anatomische 2-Bundel-Technik mit 2 tibialen und 2 femoralen Bohrkanalen und einem Allograft (Tibialis-anterior- oder Tibialis-posterior-Sehnen). Diese Technik stellt sowohl das anteromediale als auch das postero-laterale Bundel des Kreuzbandes wieder her. Trotzdem sind klinische Langzeituntersuchungen mit Messungen der Rotationsstabilitat und Erfassung von arthrotischen Veranderungen notwendig, um die Resultate der biomechanischen und ersten klinischen Untersuchungen zu bestatigen.

Early Loosening after Total Knee Arthroplasty with Minimal Incision Surgery: A Report of Two Cases and A Review of the Literature

Advances in surgical techniques and equipment have recently encouraged the use of minimal incision surgery (MIS) in total knee arthroplasty (TKA). However several complications have been reported following MIS, among which, early loosening is one of the most serious issues. We report two cases that experienced early loosening of the tibial component within three months of surgery, and received revision surgery within three years of primary MIS TKA. The cases were compared with 50 other cases which received MIS TKAs by the same technique, and it was hypothesized the failures in the two relatively young patients may have been caused by virus implantation of the tibiae component and a large bony cut in the proximal tibia, possibly as a result of limited working space during surgeries.