β1-adrenergic receptor but not β2 mediates osteogenic differentiation of bone marrow mesenchymal stem cells in normotensive and hypertensive rats

Diabetes Mellitus Impairs the Bone Regeneration Capacity of Mesenchymal Stromal Cell-Based Therapy

BACKGROUND

Diabetes mellitus (DM) negatively impacts bone tissue, leading to bone loss and increased fracture risk. Many individuals need additional treatments, and therapy based on mesenchymal stromal cells (MSCs) represents a promising treatment for bone defects in patients with diabetes.

AIMS

The present study explored the effects of interactions between MSCs from normoglycemic (NG-MSCs) and diabetic (DM-MSCs) donors on osteoblast differentiation and the effects of cell therapy using NG-MSCs on bone regeneration in defects created in diabetic rats.

METHODS

After inducing DM with streptozotocin, we evaluated the morphometric parameters of rat femurs and the osteoblast differentiation of MSCs, as well as the effects of the interaction between NG-MSCs and DM-MSCs on their osteoblast differentiation. The efficacy of cell therapy was measured by evaluating the bone repair in calvarial defects of diabetic rats treated with local injections of either NG-MSCs or a vehicle.

RESULTS

DM induced bone loss and impaired the osteoblast differentiation of MSCs, which was partially restored by NG-MSCs, while the bone formation observed in defects treated with NG-MSCs and the vehicle was similar.

CONCLUSION

These results indicate that the beneficial effect of NG-MSCs on DM-MSCs did not translate into enhanced bone repair, mainly due to a hostile environment created by hyperglycemia, which compromised the ability of MSCs to induce bone formation.

Targeting the central and peripheral nervous system to regulate bone homeostasis: mechanisms and potential therapies

The skeleton is innervated by different types of nerves and receives signaling from the nervous system to maintain homeostasis and facilitate regeneration or repair. Although the role of peripheral nerves and signals in regulating bone homeostasis has been extensively investigated, the intimate relationship between the central nervous system and bone remains less understood, yet it has emerged as a hot topic in the bone field. In this review, we discussed clinical observations and animal studies that elucidate the connection between the nervous system and bone metabolism, either intact or after injury. First, we explored mechanistic studies linking specific brain nuclei with bone homeostasis, including the ventromedial hypothalamus, arcuate nucleus, paraventricular hypothalamic nucleus, amygdala, and locus coeruleus. We then focused on the characteristics of bone innervation and nerve subtypes, such as sensory, sympathetic, and parasympathetic nerves. Moreover, we summarized the molecular features and regulatory functions of these nerves. Finally, we included available translational approaches that utilize nerve function to improve bone homeostasis and promote bone regeneration. Therefore, considering the nervous system within the context of neuromusculoskeletal interactions can deepen our understanding of skeletal homeostasis and repair process, ultimately benefiting future clinical translation.

Effects of Selective and Nonselective Beta Blockers on Bone Mineral Density in Mexican Patients with Breast Cancer

Breast cancer (BCa) is related to chronic stress and can reduce the bone mineral density (BMD) through neurochemicals related to beta-adrenergic receptor (ADRB) 1 and 2. Selective beta blockers (sBBs) and nonselective beta blockers (nsBBs) are used to treat systemic arterial hypertension (SAH) and may have osteoprotective effects, as they inhibit ADRBs. To evaluate the effects of sBBs and nsBBs on the BMD of Mexican patients with BCa. A retrospective study was conducted. We included 191 Mexican women with BCa without SAH and with SAH treated with nsBBs, sBBs, and diuretics. BMD was evaluated using a bone density scan (DEX scan). A greater average BMD (p < 0.05) was observed in patients with prior treatment with both nsBBs and sBBs (0.54 ± 0.94 and -0.44 ± 1.22, respectively) compared to patients treated with diuretics or without SAH (-1.73 ± 0.83 and -1.22 ± 0.98, respectively). Regarding the diagnosis of osteoporosis/osteopenia, no cases were observed in patients treated with nsBBs, whereas 5.6% of the patients treated with sBBs presented osteopenia. A total of 23.1% and 10.6% patients managed with diuretics or without treatment presented with osteoporosis and 61.5% and 48% patients managed with loop diuretics and without treatment presented with osteopenia, respectively (p < 0.05). Treatment with nsBBs is a promising option for the prevention and management of osteoporosis/osteopenia in Mexican patients with BCa; however, further prospective studies are needed.

Emerging roles of nerve-bone axis in modulating skeletal system

Over the past decades, emerging evidence in the literature has demonstrated that the innervation of bone is a crucial modulator for skeletal physiology and pathophysiology. The nerve-bone axis sparked extensive preclinical and clinical investigations aimed at elucidating the contribution of nerve-bone crosstalks to skeleton metabolism, homeostasis, and injury repair through the perspective of skeletal neurobiology. To date, peripheral nerves have been widely reported to mediate bone growth and development and fracture healing via the secretion of neurotransmitters, neuropeptides, axon guidance factors, and neurotrophins. Relevant studies have further identified several critical neural pathways that stimulate profound alterations in bone cell biology, revealing a complex interplay between the skeleton and nerve systems. In addition, inspired by nerve-bone crosstalk, novel drug delivery systems and bioactive materials have been developed to emulate and facilitate the process of natural bone repair through neuromodulation, eventually boosting osteogenesis for ideal skeletal tissue regeneration. Overall, this work aims to review the novel research findings that contribute to deepening the current understanding of the nerve-bone axis, bringing forth some schemas that can be translated into the clinical scenario to highlight the critical roles of neuromodulation in the skeletal system.