The musculoskeletal (MS) system consists of bone, cartilage, tendon, ligament, and skeletal muscle, which forms the basic framework of the human body. This system plays a vital role in appropriate body functions, including movement, the protection of internal organs, support, hematopoiesis, and postural stability. Therefore, it is understandable that the damage or loss of MS tissues significantly reduces the quality of life and limits mobility. Tissue engineering and its applications in the healthcare industry have been rapidly growing over the past few decades. Tissue engineering has made significant contributions toward developing new therapeutic strategies for the treatment of MS defects and relevant disease. Among various biomaterials used for tissue engineering, natural polymers offer superior properties that promote optimal cell interaction and desired biological function. Natural polymers have similarity with the native ECM, including enzymatic degradation, bio-resorb and non-toxic degradation products, ability to conjugate with various agents, and high chemical versatility, biocompatibility, and bioactivity that promote optimal cell interaction and desired biological functions. This review summarizes recent advances in applying natural-based scaffolds for musculoskeletal tissue engineering.

Identifying the changes in endogenous metabolites in response to intrinsic and extrinsic factors has excellent potential to obtain an understanding of cells, biofluids, tissues, or organisms’ functions and interactions with the environment. The advantages provided by the metabolomics strategy have promoted studies in bone research fields, including an understanding of bone cell behaviors, diagnosis and prognosis of diseases, and the development of treatment methods such as implanted biomaterials. This review article summarizes the metabolism changes during osteogenesis, osteoclastogenesis, and immunoregulation in hard tissue. The second section of this review is dedicated to describing and discussing metabolite changes in the most relevant bone diseases: osteoporosis, bone injuries, rheumatoid arthritis, and osteosarcoma. We consolidated the most recent finding of the metabolites and metabolite pathways affected by various bone disorders. This collection can serve as a basis for future metabolomics-driven bone research studies to select the most relevant metabolites and metabolic pathways. Additionally, we summarize recent metabolic studies on metabolomics for the development of bone disease treatment including biomaterials for bone engineering. With this article, we aim to provide a comprehensive summary of metabolomics in bone research, which can be helpful for interdisciplinary researchers, including material engineers, biologists, and clinicians.

Bone regeneration presents an enduring clinical barrier, particularly with the projected rise in osteoporotic fractures exceeding 6 million annually by 2050. Autografts, allografts, and xenografts remain foundational in bone repair due to their inherent osteogenic, osteoconductive, and osteoinductive capacities. However, issues such as donor site morbidity, immunogenicity, limited graft availability, and pathogen transmission risks limit their applicability. In response, recent developments in biomaterials, including ion-doped bioceramics, bioactive glass-polymer composites, and stem cell-functionalized hydrogels, aim to replicate the hierarchical structure and biochemical microenvironment of native bone. This review surveys advancements in scaffold materials over the past five years, evaluating their physicochemical properties, immune modulation potential, and clinical readiness within the context of bone tissue engineering (BTE). Specific attention is given to strategies for selecting appropriate biomaterials based on clinical needs, considering their physical and biological properties, as well as their respective advantages and limitations. Despite this progress, clinical translation remains limited; only a few engineered scaffolds have achieved regulatory approval for routine use. To accelerate adoption, efforts must focus on scalable fabrication, quantitative immune profiling, and scaffold degradation monitoring to bridge preclinical performance with clinical efficacy.

Background/Objectives: We evaluated serum and urinary biomarkers of bone and energy metabolism in an ovine osteoporosis model (Control, OVX, OVXD, OVXDS) at 0/3/8 months (M). Methods: Morning sampling; DXA (ROI ‘abdominal width’) and linear mixed models for repeated measures. Results: Only OVXDS showed severe DXA loss (Z-scores −3.29 at 3 M; −4.86 at 8 M), with ≈20% and ≈30% BMD reductions at 3 M and 8 M versus controls. OVX and OVXD remained within age-expected Z-score ranges at 8 M. At 3 M, OVXDS had hypocalcemia, markedly elevated UFEP, near-zero 25-OH-vitamin-D, and suppressed osteocalcin/NTX (depressed turnover). By 8 M, osteocalcin rose in OVXDS while NTX stayed low, consistent with altered coupling under chronic glucocorticoids and vitamin D deficiency. OVXD showed milder, later changes. Fructosamine and insulin were transiently higher in OVXDS at 3 M; IGF-1 was stable across groups/time. Conclusions: Combined ovariectomy, calcium/vitamin-D-deficient diet, and glucocorticoids produce the clearest biomarker signature and DXA loss. Assay cross-reactivity limited PTH/DKK-1/cathepsin-K measurement in sheep; we summarize DXA outcomes and expand assay limitations and future validation plans.

Immune regulation plays a crucial role during the regeneration process, and it determines the fate of inflammation after tissue injury or infection. Neutrophils serve as the primary immune cells recruited to the site of inflammation, initiating and directing the subsequent inflammatory cascade following implantation. This study investigated the effects of the in vitro standard foetal bovine serum (FBS), either in the culture medium or as a surface coating, as well as type I collagen coating on responses of neutrophils isolated from human peripheral blood using 3D-printed polycaprolactone (PCL) scaffolds. Neutrophil activity was evaluated by assessing metabolic activity and metabolomic profiles, reactive oxygen species (ROS) production, and inflammation-related markers via high throughput proximity extension assay. Type I collagen coating modified the metabolomic profile of neutrophils and MMP-9 release but had minimal effect on ROS generation. In contrast, the presence of FBS in the culture medium significantly influenced neutrophil behavior, leading to significant changes in metabolic activity, cytotoxicity, and the secretion of inflammation-associated molecules, even at concentrations as low as 1% (v/v). These findings highlight the importance of assessing the use of FBS in neutrophil culture models, particularly those isolated from humans, and emphasize the development of alternative platforms for investigating neutrophil–cell interactions in a more physiologically relevant manner. Highlights: Neutrophil response to FBS(1–10%) and collagen coatings on PCL scaffolds was tested. FBS impacts neutrophil activation and alters metabolite composition of the medium. FBS increased the release of inflammation-related molecules such as NE, IL-8 and VEGFA. Collagen changed neutrophil metabolites and decreased MMP-9 release. Results addressed the FBS bias and the need for physiologically relevant culture models. Abstract Figure:

Ex vivo bone culture models preserve aspects of the native three-dimensional bone microenvironment and may provide an intermediate platform for biomaterial screening. However, the application of dynamic-flow whole long-bone defects for time-course evaluation of bone–biomaterial interactions remains insufficiently characterized. We established a dynamic-flow ex vivo rat long-bone defect model and evaluated its capacity to maintain cell viability and to detect biomaterial-associated remodeling responses. Long bones obtained as biological by-products were subjected to standardized metaphyseal defects, with defects either left untreated or filled with injectable bone cement. Explants were maintained under continuous perfusion for 21 days. The presence of viable and membrane-compromised cells at Day 21 was assessed qualitatively by Calcein AM/propidium iodide staining; tissue morphology, mineralized bone and total ossified tissue fractions, and TRAP-positive osteoclast number were assessed on Days 7, 14, and 21. Calcein-positive cells remained detectable in the imaged regions after 21 days of dynamic-flow culture, and mineralized bone was preserved in both groups throughout this period. Cement-treated defects showed a higher mineralized tissue fraction (p < 0.001) and a higher total ossified tissue fraction (p < 0.01) than untreated defects, with no significant effect of culture time on either tissue-fraction endpoint. TRAP-positive osteoclast number was also higher in cement-treated defects (p = 0.004), and the significant Group × Time interaction (p = 0.022) indicates that this difference depended on culture duration. The findings demonstrate the feasibility of using a dynamic-flow whole-bone defect model to study bone–biomaterial interactions ex vivo. The model may serve as an intermediate experimental platform for bone–biomaterial interaction studies before in vivo evaluation.