Dehydroepiandrosterone Stimulation of Osteoblastogenesis in Human MSCs Requires IGF-I Signaling.

Dehydroepiandrosterone (DHEA) is an adrenal steroid that circulates in high concentrations in humans in its sulfated form, DHEAS. Clinical and epidemiological studies suggested that low DHEAS levels may be associated with low bone mass. Previously, we and others showed that the effects of DHEA on the skeleton may be conferred partly by their ability to inhibit skeletal catabolic agents, for example, bone resorptive cytokine IL-6. In this study, we tested the hypothesis that the anabolic effects of DHEA on osteoblastogenesis require IGF-I signaling pathways. Using both primary cultures and a cell line of human bone marrow-derived mesenchymal stem cells (hMSCs), we show that DHEA and other steroids stimulate osteoblastogenesis as shown by alkaline phosphatase activity and osteoblast gene induction. The stimulation by DHEA on both IGF-I gene expression and osteoblastogenesis in hMSCs requires IGF-I receptor, PI3K, p38 MAPK, or p42/44 MAPK signaling pathways. This study adds information to indicate that DHEA may be useful for treating bone diseases through its inhibition of skeletal catabolic IL-6 and stimulation of anabolic IGF-I-mediated mechanisms. J. Cell. Biochem. 117: 1769-1774, 2016. © 2015 Wiley Periodicals, Inc.

Return to Play and Pattern of Injury After ACL Rupture in a Consecutive Series of Elite UEFA Soccer Players.

Background: Anterior cruciate ligament rupture represents a career-threatening injury for professional soccer players. Purpose: To analyze the pattern of injury, return to play (RTP), and performance of a consecutive series of elite professional soccer players after anterior cruciate ligament reconstruction (ACLR). Study Design: Case series; Level of evidence, 4. Methods: We evaluated the medical records of 40 consecutive elite soccer players who underwent ACLR by a single surgeon between September 2018 and May 2022. Patient age, height, weight, body mass index, position, injury history, affected side, RTP time, minutes played per season (MPS), and MPS as a percentage of playable minutes before and after ACLR were retrieved from medical records and from publicly available media-based platforms. Results: Included were 27 male patients (mean ± SD age at surgery, 23.2 ± 4.3 years; range, 18-34 years). The injury occurred during matches in 24 players (88.9%), with a noncontact mechanism in 22 (91.7%). Meniscal pathology was found in 21 patients (77.8%). Lateral meniscectomy and meniscal repair were performed in 2 (7.4%) and 14 (51.9%) patients, respectively, and medial meniscectomy and meniscal repair were performed in 3 (11.1%) and 13 (48.1%) patients, respectively. A total of 17 players (63.0%) underwent ACLR with bone-patellar tendon-bone autograft and 10 (37.0%) with soft tissue quadriceps tendon. Lateral extra-articular tenodesis was added in 5 patients (18.5%). The overall RTP rate was 92.6% (25 of 27). Two athletes moved to a lower league after surgery. The mean MPS% during the last preinjury season was 56.69% ± 21.71%; this decreased significantly to 29.18% ± 20.6% (P < .001) in the first postoperative season and then increased to 57.76% ± 22.89% and 55.89% ± 25.8% in the second and third postoperative seasons. Two (7.4%) reruptures and 2 (7.4%) failed meniscal repairs were reported. Conclusion: ACLR in elite UEFA soccer players was associated with a 92.6% rate of RTP and 7.4% rate of reinjury within 6 months after primary surgery. Moreover, 7.4% of soccer players moved to a lower league during the first season after surgery. Age, graft selection, concomitant treatments, and lateral extra-articular tenodesis were not significantly associated with prolonged RTP.

Histological differences in iliac and tibial bone graft.

BACKGROUND: Cancellous bone graft is frequently used during orthopedic procedures. While the iliac crest has traditionally been the most common donor site, the proximal tibia is an alternative donor site, especially for foot and ankle procedures. This study tested the null hypothesis that the histologic composition of iliac and tibial bone grafts is similar. MATERIALS AND METHODS: Specimens from the iliac crest (n = 10) and tibia (n = 10) in excess of that needed for patients undergoing foot or ankle fusion were examined histologically. Iliac samples were taken from the anterior iliac crest. Tibial samples were harvested from the region of Gerdy's tubercle. Specimens were graded based on the percent of bone surfaces that opposed active hematopoietic marrow, with Grade I at 0%, through Grade VI at 81% to 100%. Differences between iliac and tibial grafts were evaluated with Fisher's Exact Test. RESULTS: Iliac crest and tibial bone grafts both showed trabecular fragments with abundant osteocytes. All iliac grafts contained active hematopoietic marrow. In contrast, the medullary space of tibial grafts contained fat and little hematopoietic marrow. Nine iliac grafts were graded V or VI; whereas the ten tibial bone grafts were all graded I or II (p = 0.0001). The difference in the numbers of samples in each group ranked as grade VI was also statistically significant (p = 0.005). CONCLUSION: Iliac bone grafts contained active hematopoietic marrow, whereas quiescent medullary fat predominated in tibial grafts. CLINICAL RELEVANCE: These findings raise questions about the cellular contributions of different sources of bone graft to bone healing.

Clinical characteristics influence in vitro action of 1,25-dihydroxyvitamin D(3) in human marrow stromal cells.

Vitamin D is important for bone health, with low vitamin D levels being associated with skeletal fragility and fractures. Among its other biological activities, 1,25-dihydroxyvitamin D (1,25(OH)(2) D), stimulates the in vitro differentiation of human marrow stromal cells (hMSCs) to osteoblasts, which can be monitored by increases in alkaline phosphatase enzyme activity or osteocalcin gene expression. In this study, we tested the hypotheses that age and clinical attributes of subjects influence in vitro responsiveness of hMSCs to 1,25(OH)(2) D(3) . In a cohort of subjects whose hMSCs were isolated from bone marrow discarded during hip replacement surgery for osteoarthritis, there were significant inverse correlations with age for bone mineral density, renal function, body mass index, fat mass index, and lean mass index (n = 36-53). There were significant correlations with serum 25(OH)D for serum parathyroid hormone (PTH), body mass index, fat mass index, and lean mass index (n = 47-50). In vivo-in vitro correlation analyses indicated that there were significantly greater in vitro effects of 1,25(OH)(2) D(3) to stimulate osteoblast differentiation in hMSCs obtained from subjects who were younger than 65 years of age, or who had serum 25(OH)D ≤ 20 ng/mL, elevated serum PTH, or better renal function, assessed by estimated glomerular filtration rate. The greater in vitro stimulation of osteoblast differentiation by 1,25(OH)(2) D(3) in hMSCs from vitamin D-deficient subjects suggests that vitamin D replenishment may lead to more vigorous bone formation in subjects at risk.

Effects of age on parathyroid hormone signaling in human marrow stromal cells.

Human bone marrow stromal cells (hMSCs) have the potential to differentiate into osteoblasts; there are age-related decreases in their proliferation and differentiation to osteoblasts. Parathyroid hormone (PTH), when applied intermittently in vivo, has osteoanabolic effects in a variety of systems. In this study, we compared PTH signaling and osteoanabolic effects in hMSCs from young and old subjects. There were age-related decreases in expression of PTH/PTHrP receptor type 1 (PTHR1) gene (P = 0.049, n = 19) and in PTH activation of CREB (P = 0.029, n = 7) and PTH stabilization of ß-catenin (P = 0.018, n = 7). Three human PTH peptides, PTH1-34, PTH1-31C (Ostabolin-C, Leu(27) , Cyclo[Glu(22) -Lys(26) ]-hPTH1-31), and PTH1-84 (10 nm), stimulated osteoblast differentiation with hMSCs. Treatment with PTH1-34 resulted in a significant 67% increase in alkaline phosphatase activity in hMSCs obtained from younger subjects (<50 years old, n = 5), compared with an 18% increase in hMSCs from elders (>55 years old, n = 7). Both knockdown of CREB and treatment with a protein kinase A inhibitor H-89 blocked PTH stimulation of osteoblast differentiation in hMSCs from young subjects. The PTH peptides significantly stimulated proliferation of hMSCs. Treatment with PTH1-34 resulted in an average of twice as many cells in cultures of hMSCs from young subjects (n = 4), but had no effect with hMSCs from elders (n = 7). Upregulation of PTHR1 by 24-h pretreatment with 100 nm dexamethasone rescued PTH stimulation of proliferation in hMSCS from elders. In conclusion, age-related intrinsic alterations in signaling responses to osteoanabolic agents like PTH may contribute to cellular and tissue aging of the human skeleton.