Cyclic compressive loading induces a mature meniscal cell phenotype in mesenchymal stem cells with an atelocollagen-based scaffold.

Introduction: Biomechanical stimulation is reportedly pivotal in meniscal regeneration, although its effect on mesenchymal stem cell (MSC) meniscal differentiation remains elusive. In this study, we investigated how cyclic compressive loading (CCL) could impact MSCs using three-dimensional cultures in atelocollagen-based meniscal substitute (ACMS). Methods: We extracted MSCs from the meniscus, synovium, and articular cartilage, cultured them in three-dimensional cultures, and exposed them to CCL for 7 days. We then compared the transcriptomes of MSCs treated with and without CCL. Results: Our RNA-seq analysis revealed that CCL induced significant transcriptome changes, significantly affecting chondrocyte-related genes, including SOX9, TGFB1, and PRG4 upregulation. CCL induced transcriptional differentiation of meniscus progenitors toward mature meniscal cells. Conclusion: This study unveils the potential of mechanical stress in promoting MSC meniscal differentiation within ACMS. Our investigations provide new insights for mechanisms underlying meniscal regeneration with ACMS.

Vibration acceleration enhances proliferation, migration, and maturation of C2C12 cells and promotes regeneration of muscle injury in male rats.

Vibration acceleration (VA) using a whole-body vibration device is beneficial for skeletal muscles. However, its effect at the cellular level remains unclear. We aimed to investigate the effects of VA on muscles in vitro and in vivo using the C2C12 mouse myoblast cell line and cardiotoxin-induced injury in male rat soleus muscles. Cell proliferation was evaluated using the WST/CCK-8 assay and proportion of Ki-67 positive cells. Cell migration was assessed using wound-healing assay. Cell differentiation was examined by the maturation index in immunostained cultured myotubes and real-time polymerase chain reaction. Regeneration of soleus muscle in rats was assessed by recruitment of satellite cells, cross-sectional area of regenerated muscle fibers, number of centrally nucleated fibers, and conversion of regenerated muscle from fast- to slow-twitch. VA at 30 Hz with low amplitude for 10 min promoted C2C12 cell proliferation, migration, and myotube maturation, without promoting expression of genes related to differentiation. VA significantly increased Pax7-stained satellite cells and centrally nucleated fibers in injured soleus muscles on Day 7 and promoted conversion of fast- to slow-twitch muscle fibers with an increase in the mean cross-sectional area of regenerated muscle fibers on Day 14. VA enhanced the proliferation, migration, and maturation of C2C12 myoblasts and regeneration of injured rat muscles.

Integrin α2ß1 plays an important role in the interaction between human articular cartilage-derived chondrocytes and atelocollagen gel.

Although atelocollagen gel is used as a scaffold for culturing human articular cartilage-derived chondrocytes, little is known about cell-gel interactions. In this study, we investigated the mechanism via which atelocollagen gel affects human articular cartilage-derived chondrocytes. Two types of three-dimensional cultures of human articular cartilage-derived chondrocytes (i.e., with and without atelocollagen gel) were compared. While the amount of atelocollagen gel in culture gradually decreased with time, it promoted the expression of matrix metalloproteinases (MMPs) during the early stages of culture. Genome-wide differential gene expression analysis revealed that cell membrane- and extracellular matrix-related genes were highly ranked among up- and down-regulated groups in cells cultured in the presence of atelocollagen gel. Among the integrin family of genes, the expression of integrin subunit alpha 2 and integrin subunit alpha 10 was significantly increased in the presence of atelocollagen gel. Blocking α2ß1 integrin with the specific inhibitor BTT 3033 had a significant effect on cell proliferation, MMP expression, and cell shape, as well as on the response to mechanical stimulation. Taken together, our findings indicate that the α2ß1 integrin pathway plays an important role in the interaction of atelocollagen gel with human articular cartilage-derived chondrocytes and may be a potential therapeutic target for articular cartilage disorders.

Vibration acceleration promotes endochondral formation during fracture healing through cellular chondrogenic differentiation.

Vibration acceleration through whole body vibration has been reported to promote fracture healing. However, the mechanism responsible for this effect remains unclear. Purpose of this study was to determine whether vibration acceleration directly affects cells around the fracture site and promotes endochondral ossification. Four-week-old female Wistar Hannover rats were divided into two groups (vibration [V group] and control [C group]). The eighth ribs on both sides were cut vertically using scissors. From postoperative day 3 to 11, vibration acceleration using Power Plate® (30 Hz, low amplitude [30-Low], 10 min/day) was applied in the V group. Mature calluses appeared earlier in the V group than in the C group by histological analysis. The GAG content in the fracture callus on day 6 was significantly higher in the V group than in the C group. The mRNA expressions of SOX-9, aggrecan, and Col-II in the fracture callus on day 6 and Col-X on day 9 were significantly higher in the V group than in the C group. For in vitro analysis, four different conditions of vibration acceleration (30 or 50 Hz with low or high amplitude [30-Low, 30-High, 50-Low, and 50-High], 10 min/day) were applied to a prechondrogenic cell (ATDC5) and an undifferentiated cell (C3H10T1/2). There was no significant difference in cell proliferation between the control and any of the four vibration conditions for both cell lines. For both cell lines, alcian blue staining was greater under 30-Low and 50-Low conditions than under control as well as 30-High and 50-High conditions on days 7 and 14. Vibration acceleration under 30-L condition upregulated chondrogenic gene expressions of SOX-9, aggrecan, Col-II, and Col-X. Low-amplitude vibration acceleration can promote endochondral ossification in the fracture healing in vivo and chondrogenic differentiation in vitro.