In Vitro Effects of Strontium on Proliferation and Osteoinduction of Human Preadipocytes.

Development of tools to be used for in vivo bone tissue regeneration focuses on cellular models and differentiation processes. In searching for all the optimal sources, adipose tissue-derived mesenchymal stem cells (hADSCs or preadipocytes) are able to differentiate into osteoblasts with analogous characteristics to bone marrow mesenchymal stem cells, producing alkaline phosphatase (ALP), collagen, osteocalcin, and calcified nodules, mainly composed of hydroxyapatite (HA). The possibility to influence bone differentiation of stem cells encompasses local and systemic methods, including the use of drugs administered systemically. Among the latter, strontium ranelate (SR) represents an interesting compound, acting as an uncoupling factor that stimulates bone formation and inhibits bone resorption. The aim of our study was to evaluate the in vitro effects of a wide range of strontium (Sr2+) concentrations on proliferation, ALP activity, and mineralization of a novel finite clonal hADSCs cell line, named PA20-h5. Sr2+ promoted PA20-h5 cell proliferation while inducing the increase of ALP activity and gene expression as well as HA production during in vitro osteoinduction. These findings indicate a role for Sr2+ in supporting bone regeneration during the process of skeletal repair in general, and, more specifically, when cell therapies are applied

Study of the Expression and Function of Calcium-Sensing Receptor in Human Skeletal Muscle

From MDPI via Jisc Publications RouterHistory: accepted 2021-07-02, pub-electronic 2021-07-06Publication status: PublishedFunder: H2020 Marie Skłodowska-Curie Actions; Grant(s): 675228Skeletal muscle has an outstanding capacity for regeneration in response to injuries, but there are disorders in which this process is seriously impaired, such as sarcopenia. Pharmacological treatments to restore muscle trophism are not available, therefore, the identification of suitable therapeutic targets that could be useful for the treatment of skeletal reduced myogenesis is highly desirable. In this in vitro study, we explored the expression and function of the calcium-sensing receptor (CaSR) in human skeletal muscle tissues and their derived satellite cells. The results obtained from analyses with various techniques of gene and protein CaSR expression and of its secondary messengers in response to calcium (Ca2+) and CaSR drugs have demonstrated that this receptor is not present in human skeletal muscle tissues, neither in the established satellite cells, nor during in vitro myogenic differentiation. Taken together, our data suggest that, although CaSR is a very important drug target in physiology and pathology, this receptor probably does not have any physiological role in skeletal muscle in normal conditions

The use of mouse ribs in organ culture improves the in vitro bone resorption assay

This study investigated in vitro bone resorption determining the calcium release in ribs, long bone and calvaria prelabelled with 45Ca from 17 day mouse fetuses, both in the absence and in the presence of specific stimuli, such as parathyroid hormone and calcitonin. 10- 7 M rat parathyroid hormone (1-34) (rPTH (1-34)) stimulated bone resorption (evaluated through the ratio treated ribs/control ribs) in 93% of the organ cultures, while lower success rate was obtained using calvaria and long bone from the same animals. In the absence of test substances, no differences were observed in paired ribs from the same fetus, while corresponding ribs from different fetuses showed considerable differences. Within every single hemythorax, bone resorption varies according to the rib position either in control ribs, or in those ones treated with rPTH (1-34). In the presence of rPTH (1-34), bone resorption showed to be dose-dependent producing a maximal response at 10- 6 M, a minimal response at 10- 8 M and a half-maximal response at 5x10-8 M. Salmon calcitonin (sCT) had no effect upon basal resorption, while it acted as a potent inhibiting agent in PTH response. The conspicuous number of samples which can be obtained from a relatively low number of mice, the reproducibility of results, together with the hormone sensitivity make the fetal mouse rib model an excellent tool for evaluating bone resorption in vitr

In Vitro Effects of PTH (1-84) on Human Skeletal Muscle-Derived Satellite Cells

Parathyroid hormone (PTH) is a hormone secreted by the parathyroid glands. Despite its well-known characterized anabolic and catabolic actions on the skeleton, the in vitro effects of PTH on skeletal muscle cells are limited and generally performed on animal models. The aim of this study was to evaluate the effects of a short impulse of PTH (1-84) on the proliferation and the differentiation of skeletal muscle satellite cells isolated from human biopsies. The cells were exposed for 30 min to different concentrations of PTH (1-84), from 10−6 mol/L to 10−12 mol/L. ELISA was used to assay cAMP and the myosin heavy-chain (MHC) protein. The proliferation was assayed by BrdU and the differentiation by RealTime-qPCR. A statistical analysis was performed by ANOVA followed by Bonferroni’s test. No significant variations in cAMP and the proliferation were detected in the isolated cells treated with PTH. On the other hand, 10−7 mol/L PTH on differentiated myotubes has shown significant increases in cAMP (p ≤ 0.05), in the expression of myogenic differentiation genes (p ≤ 0.001), and in the MHC protein (p ≤ 0.01) vs. untreated controls. This work demonstrates for the first time the in vitro effects of PTH (1-84) on human skeletal muscle cells and it opens new fields of investigation in muscle pathophysiology

Subcutaneous adipocytes may become osteoblasts

Commonly, mesenchymal stem cells derived from bone marrow (BMSCs) are mainly utilized in regenerative medicine field. BMSCs are able to differentiate into several lineages, showing immunosuppressive properties, and they are genetically stable in long-term cultures. In the last years, another mesenchymal stem cells population, obtained from adipose tissue, defined adipose-derived stem/stromal cells (ASCs), it is under assessment of scientific research, as alternative to BMSCs. In fact, ASCs show similar capacity to BMSCs, but unlike BMSCs can be harvested more easily with an higher yield and with less invasive manipulation. In this review the abilities of ASCs to differentiate in osteoblasts cells are show