[The short-term outcomes of non-contact low frequency ultrasonic debridement in treating periprosthetic joint infections:a prospective single-arm clinical study].

Objective: To evaluate the short-term outcomes of non-contact low-frequency ultrasonic debridement in treating periprosthetic joint infections(PJI). Methods: The clinical data of patients with PJI who met the eligibility criteria and were treated with non-contact low-frequency ultrasonic debridement from August 2021 to January 2022 at the Department of Orthopaedics,the First Affiliated Hospital of Xinjiang Medical University were prospectively analyzed. PJI was defined according to the modified Musculoskeletal Infection Society criteria in 2016. After mechanical debridement,an 8-mm handheld non-contact low-frequency ultrasound probe was used for ultrasonic debridement in the whole surgical area at a frequency of (25±5)kHz and power of 90% for 5 minutes. Each ultrasound lasted 10 seconds with 3-second intervals. The probe was repeatedly sonicated among all soft tissue,bone interface and metal prosthesis surface(patients underwent debridement,antibiotics and implant retention (DAIR)) in the surgical area. The femoral canal of the hip joint,the distal femoral canal and the posterior capsule of the knee were fully sonicated with a special right-angle probe. Before and after ultrasonic debridement,20 ml of liquid was extracted from each operation area and injected into aerobic and anaerobic culture bottles,respectively,for pathogen culture. Harris hip score and Hospital for Special Surgery (HSS) score were used to evaluate clinical function. Treatment failure was defined as the recurrence of infection in the same joint. The patients were routinely followed up in the outpatient clinic at 1,3,and 6 months postoperatively and then annually with a deadline of August 2022. The paired t-test,rank sum,Mann-Whitney U or χ2 test was used to compare the observed data,and rates among multiple groups were compared using the Bonferroni approach. Results: A total of 45 patients were included in the study,including 21 men and 24 women with age of (65.8±15.2)years(range: 20 to 80 years) and body mass index of (29.3±4.2)kg/m2(range: 20.2 to 38.5 kg/m2). Twenty-eight patients (18 hips and 10 knees) underwent one-stage revision,and 17 cases (5 hips and 12 knees) underwent DAIR. Three of the patients (6.7%) had recurrent infections during follow-up. There were no intraoperative complications related to ultrasonic debridement (neurovascular and muscle injury,poor wound healing and fat liquefaction). Seventeen patients who received DAIR were followed for a median(M(IQR)) of 9(3) months,and two relapsed 3 weeks and 3 months post-operation,respectively. In addition,28 patients who underwent one-stage revision were followed for a median of 9(2) months,and one of the patients (3.6%,1/28) had a recurrence 6 months post-operation. The culture-positive rate of preoperative aspiration was 47.6% (20/42). The data of intraoperative soft tissue culture was 86.7% (39/45). The culture-positive rate of wound liquid before ultrasonic debridement was 46.7% (21/45). And the culture-positive rate after ultrasonic debridement was (75.6% (34/45)). After sonication,the culture-positive rate of explanted prostheses was 88.9% (40/45). There was a significant difference in culture-positive rates among all five cultures (χ2=35.483,P<0.01). Further pairwise comparison showed that the culture-positive rate of wound liquid after ultrasonic debridement was higher than that before ultrasonic debridement (χ2=7.901,P=0.005) but was not significantly different from the positive rates of other cultures (all P>0.05). The median number of colonies 24 hours after ultrasonic debridement(2 240 (1 310) CFU/ml,range: 310 to 3 140 CFU/ml) was significantly higher than that before debridement(450 (550) CFU/ml,range: 10 to 910 CFU/ml) (U=43, P=0.017). The post-operative Harris ((78.6±4.2)points,range:70.5 to 85.3 points) and HSS scores((76.4±4.8)points,range: 68.5 to 84.3 points) were significantly higher than the preoperative scores((46.0±9.8)points,range: 27.5 to 64.3 points;and (45.5±10.3)points,range: 27.6 to 63.1 points) (t=-14.6,t=-12.7;both P<0.01). Conclusions: Non-contact low-frequency ultrasonic debridement can increase the culture-positive rate and lead to a favorable short-term outcome. In addition,no complications are associated with using this new technique to treat PJI.

Role of the HDAC6/STAT3 pathway in regulating PD-L1 expression in osteosarcoma cell lines.

Histone deacetylases (HDACs), initially described as histone modifiers, have more recently been verified to target various other proteins unrelated to the chromatin environment. On this basis, findings of the current study demonstrates that the pharmacological or genetic abrogation of HDAC6 in osteosarcoma cell lines down-regulates the expression of program death receptor ligand-1 (PD-L1), an important co-stimulatory molecule expressed in cancer cells, which activates the inhibitory regulatory pathway PD-1 in T cells. As shown by our results, the mechanism by which HDAC6 regulated PD-L1 expression was mediated by the transcription factor STAT3. In addition, we observed that selective HDAC6 inhibitors could inhibit tumor progression in vivo. Crucially, these results provide an essential pre-clinical rationale and justification for the necessity of further research on HDAC6 inhibitors as potential immuno-modulatory agents in osteosarcoma.

NRSN2 promotes osteosarcoma cell proliferation and growth through PI3K/Akt/MTOR and Wnt/ß-catenin signaling.

Osteosarcoma is the most common bone cancer in children and adults. However, its pathogenesis, especially molecular mechanisms remain elusive. In current study, we screened GEO Database and found a poorly studied protein Neurensin-2 (NRSN2), which is highly expressed in osteosarcoma tissues. Neurensin-2 (NRSN2) is a small neuronal membrane protein and localized in small vesicles in neural cells, previous study found that it has been implicated in hepatocellular carcinoma (HCC) and non-small cell lung cancer (NSCLC). We here report that the expression of NRSN2 is more commonlyelevated in 18 fresh osteosarcoma tissues. Furthermore, both loss- and gain-functions assays revealed that NRSN2 could promote osteosarcoma cell proliferation and growth both in vitro and in vivo. In addition, we further found that those effects on osteosarcoma by NRSN2 are associated with the dysregulated PI3K/AKT/mTOR signaling and Wnt/ß-catenin signaling. In conclusion, our study found a novel oncogenic protein, NRSN2, which promotes osteosarcoma cell proliferation and as a membrane protein, NRSN2 also could be a potential treatment target for osteosarcoma.

MicroRNA-145 regulates the differentiation of human adipose-derived stem cells to smooth muscle cells via targeting Krüppel-like factor 4.

Understanding the molecular mechanisms underlying human adipose-derived stem cell (hASC) differentiation to smooth muscle may contribute to the development of effective therapies for relevant muscle defects, such as bladder wall and urethral defects. A previous study described the differentiation of hASCs to smooth muscle cells (SMCs) by transforming growth factor-ß1 (TGF-ß1) and bone morphogenetic protein­4 (BMP4) treatment. The present study investigated whether microRNA-145 (miR­145) may be involved in the process of hASC differentiation. The expression of miR­145 was significantly increased during differentiation of ASCs to SMCs. SMC­specific genes and proteins, including a­smooth muscle actin (α­SMA), smooth muscle protein­22α(SM22α), calponin and myosin heavy chain (SM­MHC) were upregulated by transfection of a miR­145 mimic. By contrast, these factors were downregulated following introduction of antisense oligonucleotides. In addition, Krüppel­like factor 4 (KLF4) levels, which decreased during the differentiation of hASCs, were downregulated when the cells were transfected miR­145 mimics. Futhermore, inhibition of KLF4 by treatment with short­interfering­RNA against KLF4, resulted in increased expression of SMC­specific genes and proteins. In conclusion, the results of the present study demonstrated that by regulating KLF4, miR­145 may be involved in regulating smooth muscle differentiation of ASCs induced by TGF­ß1 and BMP4.

Differentiation of Human Adipose Derived Stem Cells into Smooth Muscle Cells Is Modulated by CaMKIIγ.

The multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is known to participate in maintenance and switches of smooth muscle cell (SMC) phenotypes. However, which isoform of CaMKII is involved in differentiation of adult mesenchymal stem cells into contractile SMCs remains unclear. In the present study, we detected γ isoform of CaMKII in differentiation of human adipose derived stem cells (hASCs) into SMCs that resulted from treatment with TGF-ß1 and BMP4 in combination for 7 days. The results showed that CaMKIIγ increased gradually during differentiation of hASCs as determined by real-time PCR and western blot analysis. The siRNA-mediated knockdown of CaMKIIγ decreased the protein levels and transcriptional levels of smooth muscle contractile markers (a-SMA, SM22a, calponin, and SM-MHC), while CaMKIIγ overexpression increases the transcriptional and protein levels of smooth muscle contractile markers. These results suggested that γ isoform of CaMKII plays a significant role in smooth muscle differentiation of hASCs.

Therapeutic effect of osteogenically induced adipose derived stem cells on vascular deprivation-induced osteonecrosis of the femoral head in rabbits.

OBJECTIVE: To explore the therapeutic effect of osteogenically induced adipose-derived stem cells (ADSCs) on vascular deprivation-induced osteonecrosis of the femoral head (ONFH) in rabbit model. METHODS: Vascular deprivation-induced ONFH was established by intramuscular injection of methylpre- dnisolone, and vascular occlusion of the capital femoral epiphysis by electrocoagulation in adult New Zealand white rabbits. Eight weeks after the establishment of vascular deprivation-induced ONFH, animals were randomly divided into three equal groups. In Group A (control), no therapy was given. In Group B, core decompression was performed by drilling a hole (1.2 mm in diameter) from the outer cortex 2.5 cm distal to the proximal end of the greater trochanter. In Group C, 1 multiply 10(7) osteogenically induced ADSCs were resuspended in 0.5 ml PBS, and then injected directly into the femoral head. Femoral head specimens were obtained at postoperative 8 weeks. The bone formation and three-dimensional microstructure of the femoral head was evaluated by micro-computed tomography scans. Immunohistochemical analysis was performed to detect the expression of osteocalcin. Angiogenesis and repair of the femoral head were observed histologically. RESULTS: In trabecular bone at the proximal femur region, the trabecular volume was higher in Group C (130.70 mm(3)+/-4.33 mm(3)) than that in Groups A (101.07 mm(3)+/-7.76 mm(3)) and B (107.89 mm(3)+/-8.68 mm(3), P less than 0.01). Bone volume was significantly increased in Group C (40.09 mm(3)+/-6.35 mm(3)) than in Groups A (29.65 mm(3)+/-4.61 mm(3)) and B (31.80 mm(3)+/-4.01 mm(3), P less than 0.01). The trabecular number was higher in Groups C (1.58+/-0.25) than other two groups (1.15+/-0.18, 1.16+/-0.21, P less than 0.01). Bone mineral density showed statistically significant difference between Groups C and A or B (375.38+/-23.06) mg HA/ccm, vs (313.73+/-19.30) mg HA/ccm and (316.09+/-16.45) mg HA/ccm, P less than 0.01). Histological examination indicated that there was more new bone formation in Group C than in other groups. CONCLUSION: Treatment with autologous osteogeni-cally induced ADSCs transplantation results in an enhanced osteogenesis and microstructure of the vascular deprivation-induced osteonecrosis in rabbits.

Can bisphenol A diglycidyl ether (BADGE) administration prevent steroid-induced femoral head osteonecrosis in the early stage?

Steroid-induced osteonecrosis of the femoral head (ONFH) is associated with increase of intraosseous pressure caused by elevating of adipogenesis and fat cell hypertrophy in the bone marrow, which subsequently decreases the blood flow in the femoral head and finally resulting in bone ischemia. The early femoral head-preserving method has mainly focused on the conventional core decompression procedure. However, it only achieves a slight decrease in intra-medullary pressure with limited clinical outcome. The crucial point in prevention is to achieve a thorough decompression of intra-medullary pressure and improvement of microcirculation of the femoral head. Bisphenol-A-diglycidyl ether (BADGE), an antagonism of PPAR-γ(Peroxisome proliferator-activated receptor gamma), has been shown to successfully reverse bone marrow adipogenesis and fat cell hypertrophy, enhances proliferation of osteoblasts, inhibit osteoclastogenesis. Therefore, we hypothesized that BADGE administration may be an appropriate novel method for the prevention of early stage steroid-induced ONFH.