Objective To explore the effects of mechanical stimulation on the expression of autoantigens in myoblasts. Methods According to different processing methods, C2C12 cells were divided into the experimental group and control group; the experimental group was divided into 4 subgroups: 2-, 4-, and 6-day and 1-day stretch groups. In 2-, 4-, and 6-day stretch groups, mechanical loading was added on the C2C12 cells at a stretching frequency of 0.25 Hz and cellular deformation amplitude of 10%, 2 hours a day for 2, 4, and 6 days respectively by Flexercell 5000 strain unit, and at a stretching frequency of 1 Hz and cellular deformation amplitude of 15% for 1 hour in 1-day stretch group. In the control group, the cells were routinely cultured for 1, 2, 4, and 6 days (1-, 2-, 4-, and 6-day control). The cells were observed by inverted phase contrast microscope. The cell proliferation was detected by flow cytometry; the expressions of autoantigens were detected by Western blot method, including the Ku/the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), U1-70 (A part of ATP-dependent DNA helicase II), histidyl tRNA synthetase (HRS), and Mi-2 (reconfigurable components deacetylase complexes of NuRD). Results The exfoliated cells were found in 1-day stretch group, but no exfoliated cell was seen in the control group for 1-day culture. The cells proliferated more obviously in 2-day stretch group than in the control group for 2-day culture; cell differentiation was found in 4-day stretch group, and cell fusion in 6-day stretch group, which were similar to those in the control group for 4- and 6-day culture. After single stretching, cell apoptosis was found in 1-day stretch group, showing no significant difference in the relative DNA proliferation index (DPI) when compared with DPI of control group for 1-day culture (t=0.346, P=0.747). After cyclic stretching, DPIs of 2- and 4- day stretch groups were significantly increased when compared with those of the control group for 2- and 4-day culture (P lt; 0.05), but no significant difference was found between control group for 6-day culture and 6-day stretch group (t=1.191, P=0.303). Compared with the control group for 2-day culture, the relative protein expression of autoantigens (DNA-Pkcs, Mi-2, HRS, and U1-70) in 2-day stretch group decreased significantly (P lt; 0.05), but no significant difference was found between control group for 4-day culture and 4-day stretch group (P gt; 0.05). The relative protein expressions of autoantigens in 4-day stretch group significantly increased when compared with those of 2-day stretch group (P lt; 0.05), but the relative protein expressions of autoantigens in the control group for 4-day culture significantly decreased when compared with those of the control group for 2-day culture (P lt; 0.05). Conclusion Short-term mechanical stimulation can inhibit the expressions of autoantigens in myoblasts, but with the time prolonging, cell differentiation and fusion and adaptation to mechanical stimulation would result in diminished inhibitory effect.
Objective To evaluate the early effectiveness of total talar replacement (TTR) with personalized three-dimensional (3D)-printed titanium talus prostheses in the treatment of steroid-induced talar avascular necrosis (TAN). Methods The clinical data of 11 patients with steroid-induced TAN who met the selection criteria between June 2022 and June 2024 were retrospectively analyzed. There were 8 males and 3 females with an average age of 51 years ranging from 26 to 67 years. The duration of hormone use ranged from 12 to 36 months, with an average of 19.6 months. The TTR treatment was performed with the personalized 3D-printed titanium alloy talus prosthesis. Radiographic evaluation was performed preoperatively and at last follow-up to assess prosthesis-related conditions, including loosening, subsidence, and adjacent joint degeneration. Clinical outcomes were assessed using the visual analogue scale (VAS) score, American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Ankle Osteoarthritis Scale (AOS), 36-Item Short Form Survey (SF-36) [including physical health score (PCS) and mental health score (MCS)], and ankle range of motion (ROM) to assess functional recovery. Results All surgeries were completed successfully. The operation time was 40-60 minutes (mean, 51 minutes), and intraoperative blood loss was 5-20 mL (mean, 10 mL). All incisions healed by first intention without early complications such as infection, skin necrosis, hematoma, neurovascular injury, or deep vein thrombosis. All 11 patients were followed 15-33 months (mean, 22.8 months). One superficial wound infection occurred at 2 weeks postoperatively and resolved after conservative treatment. No prosthetic joint infection, loosening, subsidence, adjacent joint degeneration, or reoperation was observed. At last follow-up, the VAS score, AOFAS ankle-hindfoot score, AOS score, PCS score, and MCS score improved significantly when compared with preoperative ones (P<0.05), whereas ankle ROM showed no significant difference (P>0.05). Conclusion Personalized 3D-printed titanium talus prostheses effectively relieve pain and improve ankle function and quality of life in patients with steroid-induced TAN, providing a viable joint-preserving treatment option.