Aims. In our previous research, we have found that melatonin (MEL) affects the osteoporotic process. By balancing bone remoulding, autophagy is involved in age-related bone loss. However, as a regulator of autophagy, whether MEL influences senile osteoporosis via regulating autophagy remains unclear. Methods. Cellular, radiological, and histopathological evaluations were performed on 36 16-month-old male C57BL6/L mice or aged bone marrow-derived mesenchymal stem cells. A MEL-gelatin methacrylamide system was constructed to aid osteoporotic fracture healing. Results. In this study, we found that bone loss, low level of MEL, and decreased autophagy coexisted in aged C57BL6/L mice. A physiological (low, 10 nM but not 100 nM) concentration of MEL restored bone loss, transformed the cytokine framework, and increased the autophagic level in aged mice, whereas inhibition of autophagy unfavourably reduced the positive effects of MEL on bone mass. The autophagy-conducted increased osteogenic lineage commitment and extracellular matrix mineralization, but not matrix synthesis of aged bone marrow-derived mesenchymal stem cells, was responsible for MEL anabolic effects on bone. PIK3C-AKT-MTOR signal was tested to be a main pathway that is involved in MEL-induced autophagy. Conclusion. Our data suggest that the application of MEL can restore degenerative osteogenesis of aged bone marrow-derived mesenchymal stem cells, and has the potential to regain bone mass in aged mice through activating autophagy via the PIK3C-AKT-MTOR pathway. MEL therefore may serve as a potential clinical therapy to treat senile osteoporosis. Cite this article: Bone Joint Res 2025;14(2):97–110

Introduction and Objective. Senescent bone cell overburden accelerates osteoporosis. Epigenetic alteration, including microRNA signalling and DND methylation, is one of prominent features of cellular senescence. This study aimed to investigate what role microRNA-29a signalling may play in the development of senile osteoporosis. Materials and Methods. Bone biopsy and serum were harvested from 13 young patients and 15 senior patients who required spine surgery. Bone mass, microstructure, and biomechanics of miR-29a knockout mice (miR-29aKO) and miR-29a transgenic mice (miR-29aTg) were probed using mCT imaging and three-point bending material test. Senescent cells were probed using senescence-associated b-galactosidase (SA-b-gal) staining. Transcriptomic landscapes of osteoblasts were characterized using whole genome microarray and KEGG bioinformatics. miR-29a and senescence markers p16. INK4a. , p21. Waf/cipl. and inflammatory cytokines were quantified using RT-PCR. DNA methylome was probed using methylation-specific PCR and 5-methylcytosine immunoblotting. Results. Senescent osteoblast overburden, DNA hypermethylation and oxidative damage together with significant decreases in serum miR-29a levels were present in bone specimens of aged patients. miR-29aKO mice showed a phenotype of skeletal underdevelopment, low bone mineral density and weak biomechanics. miR-29a knockout worsened age-induced bone mass and microstructure deterioration. Of note, aged miR-29aTg mice showed less bone loss and fatty marrow than aged wild-type mice. Transgenic overexpression of miR-29s compromised age-dysregulated osteogenic differentiation capacity of bone-marrow mesenchymal cells. In vitro, miR-29a promoted transcriptomic landscapes of antioxidant proteins in osteoblasts. The microRNA interrupted DNA methyltransferase (Dnmt3b)-mediated DNA methylation, inhibiting reactive oxygen radicals burst, IL-6 and RANKL production, and a plethora of senescent activity, including increased p16. INK4a. , p21. Waf/cipl. signalling and SA-b-gal activity. Conclusions. miR-29a loss is correlated with human age-mediated osteoporosis. miR-29a signalling is indispensable in bone mase homeostasis and microstructure integrity. Gain of miR-29a function is advantageous to delay age-induced bone loss through promoting antioxidant proteins to inhibit DNA hypermethylation-mediated osteoblast senescence. Collective investigations shine light onto the anabolic effects miR-29a signalling to bone integrity and highlight a new epigenetic protection strategy through controlling microRNA signalling to delay osteoblast senescence and senile osteoporosis development

Relating the results of our investigations to the knowledge hitherto acquired about the etiology of osteoporosis (which I have already referred to), I am inclined to interpret the pathogenesis of osteoporosis in the following way: 1) Primary osteoblastic deficiency: congenital (Lobstein); involutive (senile osteoporosis?); 2) Reduced osteoblastic activity from absence of trophic stimuli: (inactivity, ovarian agenesia, eunuchoidism, menopause); 3) Reduced osteoblastic activity from inhibitory stimuli: (cortisone, adrenocorticotrophic hormone (A.C.T.H.), stress, Cushing's disease, thyrotoxicosis); 4) Normal osteoblastic activity but insufficiency of constructive material: (malnutrition, disturbances of the digestive system, insufficiency of vitamin C, diabetes, thyrotoxicosis, cortisone, A.C.T.H., stress, Cushing's disease). Osteoporosis may therefore be the consequence either of a congenital osteoblastic deficiency, such as that found in cases of osteogenesis imperfecta, or of reduced osteoblastic activity due to absence of trophic stimuli such as mechanical stress and the sex hormones, or of reduced activity of the bone cells due to anti-anabolic substances which inhibit them, such as cortisone and its derivatives and the thyroid hormone in strong doses, or lastly of reduced availability of construction material due to its introduction in reduced quantities (starvation, dysfunction of the digestive system) or due to hindering of synthesis (deficiency of vitamin C, diabetes, cortisone and its derivatives) or due to an excessive degree of destruction (thyrotoxicosis). In the case of anti-anabolic hormones from the adrenal cortex, the mechanism may thus be twofold: inhibition of the osteoblasts and deprivation of the osteoblasts of glucoprotein material due to a general anomaly of metabolism. This may perhaps explain the most serious forms of bone atrophy which are usually observable in cases of hyperfunction of the adrenal cortex. Senile osteoporosis should, in my opinion, be included in the first of our groups because it cannot be said to be brought about by any of the causes usually cited for osteoporosis– such as deficiency of sex hormones, excess of hormones from the adrenal cortex, deficiency of calcium, etc.–and in all probability it will depend on a progressive involution of the osteoblasts brought about by old age. Senile involution is an expression of the descending phase of life's parabola and it involves all the organs and all the parenchymatous tissues in the human body, but it does not cause a parallel reduction of functions and activities on all of them equally. The skeletal system is one of the first to feel these reductions, because in old age life necessarily becomes less intense. Consequently in the economy of the ageing subject the generally reduced level of metabolism brings about a sort of selection in the nourishment of the different organs and systems, and sometimes almost a dismantling of some of these in an attempt to fall in with the new and reduced level of activities of some of the parenchymatous tissues, activities which may be incomplete or even transferred elsewhere. We believe that the moment which originally determines the beginning of senile osteoporosis coincides with the involutional process of cellular metabolism that strikes at all parenchymatous tissue during old age–striking, in the case of osteoporosis, hardest of all at the bony tissues. There is, indeed, no doubt that certain essential processes of cellular metabolism do alter with age, and that the reduction in the activity of the gonads does have considerable importance. In any case, just as adolescence and old age cannot be explained only in terms of gonadal activity, so the involution of the skeleton cannot be due merely to the involution of the gonads. How should one then interpret the well known benefit afforded by administration of sex hormones in cases of osteoporosis? Probably the action of oestrogens and androgens is, in this case, of a pharmacological nature, and comparable, for instance, to the action of digitalis on the cardiac muscle. It will be remembered how digitalis acts almost exclusively on myofibrils which have become inadequate, and has little or no effect on a normal myocardium. Similarly, the sex hormones would seem to exert a stimulating action on osteoblasts that are on the way to involution, while they exert little or no action on normal osteoblasts. In support of this we have the findings of Urist and other workers, who demonstrated that the administration of sex hormones produces calcium and nitrogen retention only in osteoporotics, while in non-osteoporotic subjects of the same age it produces no effect. On the other hand, the action of the sex hormones might act in cases of senile osteoporosis by returning the changed level of protein metabolism to normal. From the data in the literature and from the results of our own investigations, I conclude that osteoporosis in general, and senile osteoporosis in particular, are first and foremost the result of a disturbance in the metabolism of bone, and that the metabolic disturbance is closely and exclusively related to the degree of activity and the state of activity of the cells in the bone. Lastly, I believe that senile osteoporosis should not be considered an actual disease but rather as one limited aspect of the normal descending parabola which affects to a greater or less degree all the tissues of the body

Introduction: Osteoporosis, a major public health burden, is associated with increased fracture risk. Fracture healing in osteoporosis is altered with reduced callus formation and impaired biomechanical properties of newly formed bone leading to high risk of fixation failure. Experimental data have shown decreased healing potential in aged animals and in animal models of post-menopausal bone loss. It is unclear whether fracture healing is similarly impaired in senile osteoporosis. The objective of this study is to investigate fracture healing in a small animal model of senile osteoporosis, senescence-accelerated mouse prone 6 (SAMP6). Materials & Methods: A mid-femur osteotomy was created in SAMP6-mice (n=24) and senescence-resistant inbred strains (SAMR1) (n=24) were used as controls. The osteotomy was rigidly fixed using a newly developed screw-plate-implant (MouseFix). Fracture healing was evaluated at 7, 14, 28 and 42 days after surgery using micro-CT and histomorphometry. Biochemical marker for bone formation (osteocalcin) and bone resorption (TRAP5b) were evaluated from serum samples. MSC were extracted from the femurs of mice and cultured in vitro and differentiated into either osteoblasts or adipocytes using standard induction media. Results: Studies carried out in vitro confirmed that MSC isolated from the bone marrow of SAMP6 mice had a reduced tendency to differentiate toward the osteoblast cell lineage as previously reported in human osteoporotic patients. Although osteoblastogenesis was clearly impaired, the formation of new bone in SAMP6 mice was comparable to that observed in SAMR1 mice. Similar results were found for histomorphometry data analyzing the degree of bone mineralisation. Interestingly, osteocalcin levels were significantly increased in serum samples from osteoporotic mice at day 7 and 14 following fracture. Discussion: The data presented here indicates that fracture healing proceeds normally in a mouse model for senile osteoporosis. This finding supports the clinical observation that although fracture fixation is difficult in osteoporosis, healing potential seems to be unchanged. MSC from osteoporotic patients as wells as from SAMP6-mice show reduced proliferation rate together with adipogenic rather than osteogenic differentiation pattern. However, decreased cell dynamics seems not to influence diaphyseal fracture healing. Other sources of MSC other than bone marrow-derived MSC may therefore be pivotal in determining the outcome of intramembranous bone repair in both normal and osteoporotic bone

1. Using the incidence of hip fracture as an indication of senile osteoporosis, the occurrence of this disease is found to vary greatly in different racial groups. The highest reported incidence is in Sweden, followed by Britain, Hong Kong Chinese, Singapore Chinese and South African Bantu, in that order. Likewise, the sex incidence varies, women outnumbering men in Sweden and Britain, men exceeding women in Singapore; an equal sex incidence is found in Hong Kong. 2. In all races and in both sexes the incidence is more closely related to age than any other factor, a progressive increase being noted after forty-five. Ageing is clearly the dominant etiological factor, but this does not explain the different racial incidence. These differences cannot be attributed to hormonal state or to the dietary intake of calcium, but do accord in general with the living standards of the different countries and the degree of physical activity undertaken by the different populations and sexes. 3. Hereditary factors may play a part, but further geographical study of the incidence of senile osteoporosis is necessary before the relative importance of inheritance and environment can be assessed

1. Senile osteoporosis is one of the common causes of morbidity in old people. Its distribution in European and American populations has been deduced from epidemiological studies of its major complications, such as fractures of the vertebrae and the femoral neck. Although there has been some evidence that different population groups differ in their susceptibility to this condition, no demographic study of its prevalence in the white and Bantu races has previously been made. 2. The present paper describes an epidemiological study of femoral neck fractures in the Bantu population of Johannesburg, covering the years 1957-63. The cases were analysed by age and sex, the type of trauma and the level of the fracture. The number of fractures was related to the population at risk; the fracture incidence was expressed both as an age-specific rate and as a standardised rate and compared with fracture rates in European populations. It was found that the fracture rate in the elderly Bantu is less than one-tenth of that in Western European populations, and that males and females are affected equally. It was concluded that senile or post-menopausal osteoporosis is much less pronounced in the Bantu than in white populations. 3. The relationship of these findings to endocrine changes, calcium balance and racial factors is discussed. It is suggested that senile osteoporosis is not caused by a simple calcium deficiency but may be related to an imbalance between calcium intake, absorption and excretion, or a failure of the complex mechanism which normally controls this balance. Whatever the immediate cause, however, race plays an important part in determining the onset and distribution of the condition

1. The clinical features, diagnosis and treatment of osteomalacia are discussed in relation to thirty-seven recently recognised cases. It is suggested that this disease is not uncommon in elderly women, among whom it is liable to be confused with senile osteoporosis. Osteomalacia may be distinguished by, firstly, the history, in which persistent skeletal pain of long duration and muscular weakness are typical of osteomalacia, but not of osteoporosis in which transient episodes of pain usually associated with a fracture are more characteristic. There is a high incidence of previous gastric surgery in the osteomalacia patients. Secondly, the physical examination shows skeletal tenderness in osteomalacia but this is not a particular feature of osteoporosis. A shuffling "penguin gait" suggests osteomalacia. Thirdly, the biochemistry shows a low plasma calcium and phosphate, and raised alkaline phosphatase levels commonly in osteomalacia but these are usually normal in osteoporosis. Reduced twenty-four-hour urinary calcium is characteristic of osteomalacia but not of osteoporosis. Fourthly, radiology will show diminished bone density which is common to both diseases, but if the changes are more marked in the peripheral bones than in the axial skeleton osteomalacia is suggested; the opposite is typical of osteoporosis. Skeletal deformity without fracture suggests osteomalacia, as do stress fractures and greenstick fractures in the elderly. Looser's zones are diagnostic of osteomalacia in which they are the most important radiological feature. Finally, histology will show the presence of excess osteoid tissue in undecalcified sections of bone in osteomalacia. This may be the earliest and most sensitive index of the disease and biopsy is indicated in all doubtful cases. 2. The etiology is discussed and it is suggested that a dietary deficiency of vitamin D, limited exposure to sunlight and mild degrees of malabsorption may all be important either alone or in combination. No satisfactory explanation is offered for the predominant female incidence. 3. A practical method of treatment is given and the dangers of uncontrolled administration of vitamin D indicated. 4. Treatment of osteomalacia is rapidly and consistently successful, and well justifies a thorough screening of all elderly patients presenting with weakness, skeletal pain, pathological fractures or with diminished radiographic density of bone

Mesenchymal Stem Cells (MSCs) are key regulators in senile osteoporosis and in bone formation and regeneration. MSCs are therefore suitable candidates for stem cells mediated gene therapy of bone. Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is a highly osteoinductive cytokine, promoting osteogenic differentiation of MSCs. We hypothesized that genetically engineered MSCs, expressing rhBMP2, can be utilized for targeted cell mediated gene therapy for local and systemic bone disorders and for bone/cartilage tissue engineering. Engineered MSCs expressing rhBMP-2 have both autocrine and paracrine effects enabling the engineered cells to actively participate in bone formation. We conditionally expressed rhBMP2 (tet-controlled gene expression, tet-off system) in mouse and human mesenchymal stem cells. RhBMP2 expressing clones (tet-off and adeno-BMP2 infected MSCs), spontaneously differentiated into osteogenic cells in vitro and in vivo. Engineered MSCs were transplanted locally and tracked in vivo in radial segmental defects (regenerating site) and in ectopic muscular and subcutaneous sites (non-regenerating sites). In vitro and in vivo analysis revealed rhBMP2 expression and function, confirmed by RT-PCR, ELISA, western blot, immunohistochemistry and bioassays. Secretion of rhBMP2 in vitro was controlled by tetracycline and resulted in secretion of 1231 ng/24 hours/106 cells. Quantitative Micro-CT 3-Dimentional reconstruction revealed complete bone regeneration regulated by tetracycline in vivo, indicating the potential of this platform for bone and cartilage tissue engineering. Angiogenesis, a crucial element in tissue engineering, was increased by 10-folds in transplants of rhBMP2 expressing MSCs (tet-off), shown by histomorphometry and MRI analysis (p< 0.05). In order to establish a gene therapy platform for systemic bone disorders, MSCs with tet-controlled rhBMP-2 expression, were injected systemically (iv). These engineered MSCs were genetically modified in order to achieve homing to the bone marrow. Systemic non invasive tracking of engineered MSCs was achieved by recording topographical bioluminescence derived from luciferase expression detected by a coupled charged CCD imaging camera. For clinical situations that require immuno-isolation of transplanted cells, we developed an additional platform utilizing cell encapsulation technique. Immuno-isolated engineered MSCs, with tet-controlled rhBMP-2 expression, encapsulated with sodium alginate induced bone formation by paracrine effect of secreted rhBMP-2. Finally, we have characterized a novel tissue-engineering platform composed of engineered MSCs and biodegradable polymeric scaffolds, creating a 3D bone tissue in rotating Bioreactors. Our results indicate that engineered MSCs and polymeric scaffolds can be utilized for ex vivo bone tissue engineering. We therefore conclude that genetically engineered MSCs expressing rhBMP-2 under tetracycline control are applicable for: a) local and systemic gene therapy to bone, and b) bone tissue engineering. Our studies should lead to the creation of gene therapy platforms for systemic and local bone diseases in humans and bone/cartilage tissue engineering

Aims

To investigate the effects of senescent osteocytes on bone homeostasis in the progress of age-related osteoporosis and explore the underlying mechanism.

Aims

With the ageing population, fragility fractures have become one of the most common conditions. The objective of this study was to investigate whether microbiological outcomes and fracture-healing in osteoporotic bone is worse than normal bone with fracture-related infection (FRI).

Aims

The effect of the gut microbiota (GM) and its metabolite on bone health is termed the gut-bone axis. Multiple studies have elucidated the mechanisms but findings vary greatly. A systematic review was performed to analyze current animal models and explore the effect of GM on bone.

Objectives

The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models.

Objectives

In order to screen the altered gene expression profile in peripheral blood mononuclear cells of patients with osteoporosis, we performed an integrated analysis of the online microarray studies of osteoporosis.