The piRNA pathway is essential for female fertility in golden hamsters and likely humans, but not in mice. However, the role of individual PIWIs in mammalian reproduction remains poorly understood outside of mice. Here, we describe the expression profiles, subcellular localization, and knockout-associated reproductive defects for all four PIWIs in golden hamsters. In female golden hamsters, PIWIL1 and PIWIL3 are highly expressed throughout oogenesis and early embryogenesis, while knockout of PIWIL1 leads to sterility, and PIWIL3 deficiency results in subfertility with lagging zygotic development. PIWIL1 can partially compensate for TE silencing in PIWIL3 knockout females, but not vice versa. PIWIL1 and PIWIL4 are the predominant PIWIs expressed in adult and postnatal testes, respectively, while PIWIL2 is present at both stages. Loss of any PIWI expressed in testes leads to sterility and severe but distinct spermatogenesis disorders. These findings illustrate the non-redundant regulatory functions of PIWI-piRNAs in gametogenesis and early embryogenesis in golden hamsters, facilitating study of their role in human fertility.

While bone marrow-derived mesenchymal stem cells (BMSC) are established sources for stem cell-based cartilage repair therapy, articular cartilage-derived mesenchymal stem cells from osteoarthritis patients (OA-MSC) are new and potentially attractive candidates. We compared OA-MSC and BMSC in chondrogenic potentials, gene expression, and regulation by miR-365, a mechanical-responsive microRNA in cartilage (Guan et al., FASEB J 25: 4457–4466, 2011). To overcome the limited number of OA-MSC, a newly established human OA-MSC cell line (Jayasuriya et al., Sci Rep 8: 7044, 2018) was utilized for analysis and comparison to BMSC. Chondrogenesis was induced by the chondrogenic medium in monolayer cell culture. After chondrogenic induction, chondrogenesis and mineralization were assessed by Alcian blue and Alizarin red staining respectively. MiRNA and mRNA levels were quantified by real-time PCR while protein levels were determined by western blot analysis at different time points. Immunohistochemistry was performed with cartilage-specific miR-365 over-expression transgenic mice. Upon chondrogenic induction, OA-MSC underwent rapid chondrogenesis in comparison to BMSC as shown by Alcian blue staining and activation of ACAN and COL2A1 gene expression. Chondrogenic induction also activated mineralization and the expression of hypertrophic and osteogenic genes in OA-MSC while only hypertrophic genes were activated in BMSC. MiR-365 expression was activated by chondrogenic induction in both OA-MSC and BMSC. Transfection of miR-365 in OA-MSC induced chondrogenic, hypertrophic, and osteogenic genes expression while miR-365 inhibition suppressed the expression of these genes. Over-expression of miR-365 upregulated markers of OA-MSC and hypertrophy and increased OA scores in adult mouse articular cartilage. Induction of chondrogenesis can activate mineralization, hypertrophic, and osteogenic genes in OA-MSC. MiR-365 appears to be a master regulator of these differentiation processes in OA-MSC during OA pathogenesis. These findings have important implications for cartilage repair therapy using cartilage derived stem cells from OA patients.

Background: There is currently no ideal treatment for osteochondral lesions of the femoral head (OLFH) in young patients. Methods: We performed a 1-year single-arm study and 2 additional years of follow-up of patients with a large (defined as >3 cm²) OLFH treated with insertion of autologous costal cartilage graft (ACCG) to restore femoral head congruity after lesion debridement. Twenty patients ≤40 years old who had substantial hip pain and/or dysfunction after nonoperative treatment were enrolled at a single center. The primary outcome was the change in Harris hip score (HHS) from baseline to 12 months postoperatively. Secondary outcomes included the EuroQol visual analogue scale (EQ VAS), hip joint space width, subchondral integrity on computed tomography scanning, repair tissue status evaluated with the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, and evaluation of cartilage biochemistry by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping. Results: All 20 enrolled patients (31.02 ± 7.19 years old, 8 female and 12 male) completed the initial study and the 2 years of additional follow-up. The HHS improved from 61.89 ± 6.47 at baseline to 89.23 ± 2.62 at 12 months and 94.79 ± 2.72 at 36 months. The EQ VAS increased by 17.00 ± 8.77 at 12 months and by 21.70 ± 7.99 at 36 months (p < 0.001 for both). Complete integration of the ACCG with the bone was observed by 12 months in all 20 patients. The median MOCART score was 85 (interquartile range [IQR], 75 to 95) at 12 months and 75 (IQR, 65 to 85) at the last follow-up (range, 24 to 38 months). The ACCG demonstrated magnetic resonance properties very similar to hyaline cartilage; the median ratio between the relaxation times of the ACCG and recipient cartilage was 0.95 (IQR, 0.90 to 0.99) at 12 months and 0.97 (IQR, 0.92 to 1.00) at the last follow-up. Conclusions: ACCG is a feasible method for improving hip function and quality of life for at least 3 years in young patients who were unsatisfied with nonoperative treatment of an OLFH. Promising long-term outcomes may be possible because of the good integration between the recipient femoral head and the implanted ACCG. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Mosaic transplantation using autologous osteochondral graft (AOCG) is an effective treatment for osteochondral lesion however, at the sacrifice of irreversible damage to the donor articular surface. Costal cartilage is hyaline cartilage and has been utilized as a donor source in various surgeries. This study investigates the use of autologous costal cartilage graft (ACCG) for treating femoral head osteochondral defects in a swine model. Osteochondral defects were surgically induced in the femoral heads of one-year-old Bama pigs regardless of sex. The swine were divided into a Defect group without grafting (n = 6), a group grafted with ACCG (n = 6) and a group grafted with AOCG from ipsilateral trochlear groove (n = 6). Postoperatively, swine were allowed free cage activity without immobilization and were euthanized at either 3 or 6 months. Repair effects were evaluated using μCT, MRI, histology and immunohistochemistry (IHC) to assess the osteochondral properties of the grafted femoral head. There was no difference in the hip function of the Bama pigs between AOCG and ACCG groups. The International Cartilage Repair Society (ICRS) scores showed no difference between AOCG and ACCG at both time points. ACCG exhibited comparable trabecular thickness as AOCG's, but lower trabecular number and higher trabecular separation. Percent bone volume was significantly lower in the ACCG group when compared to AOCG at 3 months, but not at 6 months. Modified MOCART scores were significantly higher in the AOCG group at 3 months but not at 6 months. MRI also detected increasing degree of ossification in the costal cartilage graft at all time points. Histologically, ACCG formed a subchondral bone interface while maintaining the hyaline cartilage characteristics on the articular surface. We also found that superficial layer of ACCG integrated more thoroughly with the recipient cartilage than AOCG did. Furthermore, histology and IHC collectively demonstrated that ACCG had undergone endochondral ossification process at the subchondral layer, evidenced by increased type I collagen expression and decreased type II collagen expression. No donor-site morbidity was noted with ACCG procedure during the study. This study demonstrates that ACCG can serve as a viable alternative to AOCG for treating femoral head osteochondral defects. The findings show that ACCG offers comparable outcomes to AOCG while avoiding the donor-site morbidity associated with AOCG. Given the challenges related to the donor tissue availability and associated complications in the clinical practice, ACCG could provide a promising and less invasive option for cartilage repair. This proposed method can be translated into practical treatment for repairing osteochondral lesion in human hip joints and provide a new avenue for treating osteochondral lesions in large joints.

Case: We describe a patient with advanced Kienböck's disease, treated with 3-dimensional (3D) printing assisted costochondral transplantation. Cartilage shaping was achieved according to a biomimetic 3D-printed prosthesis designed by mirror symmetry of the healthy wrist. The inserted cartilage spacer was fixed using the autologous palmar longus tendon. After 14 months of follow-up, the patient had significant pain relief and had recovered nearly the full range of wrist motion. No significant absorption or osseous metaplasia of the cartilage was seen on the radiographic and magnetic resonance images. Conclusion: This costochondral transplantation strategy may offer a feasible treatment option for patients with severe Kienböck's disease.