Type 1 collagen: Synthesis, structure and key functions in bone mineralization

Promoting collagen synthesis: a viable strategy to combat skin ageing

Skin ageing is a complex physiological process primarily characterised by the deepening of wrinkles and the sagging of the skin. Collagen is essential for maintaining skin elasticity and firmness. As skin ages, it experiences structural and functional changes in collagen, including a decrease in collagen synthesis and an increase in collagen hydrolysis. Thus, promoting collagen synthesis represents a practical strategy for mitigating skin ageing. This review systematically described the functions, classifications and biosynthesis process of collagen, as well as its role in skin ageing. Additionally, the major signalling pathways and targets associated with collagen synthesis were also discussed. More importantly, the review provided a detailed summary of natural products with collagen synthesis-promoting effects and highlighted small molecule compounds with potential anti-ageing activity, especially PPARδ agonists. The relevant content offers potential targets and lead compounds for the development of anti-skin ageing therapies.

The characterization and comparison of femoral bone-derived skeletal stem cells

Skeletal stem cells (SSCs) reside in various niche locations within long bones to maintain bone homeostasis and facilitate fracture repair. Bone fragility, associated with ageing, increases the susceptibility of the femoral head to fractures due to an increase in bone adipocytes and concomitant loss of structural integrity. However, the specific contribution of epiphyseal SSCs to fragility is unknown. To explore this, a comparative analysis was performed on the transcriptional profiles and lineage commitment of Wistar rat femoral SSCs derived from the bone marrow (BM-), diaphyseal cortical bone (CB-) and proximal epiphyseal trabecular bone (PF-SSCs) isolated from the same long bones. SSCs were characterized based on morphology, immunophenotype (CD90/CD45), growth rate (population doubling time), gene expression profiles and differentiation capacity (Oil Red O, Alizarin Red S). qRT-PCR micro-arrays were performed on SSCs to evaluate the expression of stemness, SSC and lineage-specific markers in both undifferentiated and differentiated states. Our findings support the hypothesis that SSCs from different bone regions exhibit distinct transcriptional profiles, reflecting their specific niche environments. CB-SSCs displayed superior osteogenic potential as evidenced by the expression of key osteogenic genes and higher levels of mineralization. In contrast, PF-SSCs had a reduced osteogenic capacity with a higher adipogenic potential. Overall, the study revealed the importance of niche-specific stem cell properties for use in regenerative medicine applications and provides insight into the potential role of PF-SSCs in bone fragility and fracture risk.

A comprehensive analysis of two types of xenogeneic bone particles for use in maxillofacial bone regeneration therapies

Regeneration of maxillofacial bone structures is challenging. One strategy for bone damage repair involves using bone filler particles. This study analyzed the regenerative potential of deproteinized bone particles (DP) and collagen-based bone particles (CP) to determine the effectiveness of each biomaterial in bone repair. Structural analysis using scanning electron microscopy and 3D scanning showed that DP and CP were structurally similar, comprising a heterogeneous mixture of bone particles of varying sizes and shapes. Ex vivo analyses, including morphological evaluation, LIVE & DEAD assays, and DNA quantification, demonstrated high biocompatibility of CP and DP with human cells in both direct and indirect contact at 24, 48, and 72 hours. Both particles were grafted onto Wistar rats with a critical mandibular defect for two months. Computed tomography revealed significant defect reduction in the CP group, but not in the DP group, compared to negative controls without any bone particles. Histological analysis showed biocompatibility of both particles in vivo and identified regenerative tissue with collagen fibers and mineralized spots in CP and DP, with more mineralized spots in DP. Histochemistry and immunohistochemistry confirmed collagen, proteoglycans, and osteocalcin presence in the regeneration area of CP and DP. These results confirm the biocompatibility and potential of both particle types for maxillofacial bone regeneration, particularly CP. Future studies should assess their clinical usefulness for patients with cleft palate, mandibular damage, and other maxillofacial applications involving tissue engineering techniques.

In Silico Screening and Identification of Functional Peptides from Yak Bone Collagen Hydrolysates: Antioxidant and Osteoblastic Activities

Collagen peptides are recognized for their diverse bioactivities; however, efficiently screening potent peptides from hydrolysates remains challenging. This study employed an integrated strategy that combined in silico antioxidant activity prediction and molecular docking to myeloperoxidase (MPO) to screen active peptides derived from yak bone collagen hydrolysates. Focusing on low molecular weight peptides, containing motifs such as GVM, GLP, GPM, and GPQ, we identified nine antioxidant peptides (KC1-KC9). Their activities were validated through in vitro free radical scavenging assays, with peptide KC7 demonstrating superior performance. Furthermore, peptide KC7 promoted proliferation, differentiation, and mineralization in MC3T3-E1 cells by upregulating osteogenic markers such as Runx2 and osteocalcin, modulating the Wnt/β-catenin and PI3K/Akt pathways, and reducing the Bax/Bcl-2 ratio. These results highlight KC7's dual capacity to mitigate oxidative stress and potentially reduce apoptotic susceptibility, thereby stimulating osteogenesis. This positions peptide KC7 as a promising candidate for bone regeneration and oxidative stress-related disorders. Moreover, this study underscores the effectiveness of integrating computational and experimental approaches for the discovery of multifunctional natural peptides.

Endogenous dysregulated energy and amino acid metabolism delay scaffold-guided large volume bone regeneration in a diabetic rat model with Leptin receptor deficiency

Scaffold-guided bone regeneration (SGBR) offers a promising solution for treating large-volume bone defects. However, its efficacy in compromised healing environments, such as those associated with metabolic conditions like Type 2 Diabetes (T2D), remains poorly understood. This study evaluates the potential of 3D-printed polycaprolactone (PCL) scaffolds for large-volume bone regeneration in preclinical models simulating T2D-induced metabolic challenges. Our results reveal that scaffolds alone are insufficient to overcome the metabolic barriers to effective bone regeneration. Metabolomic analysis of regenerating tissue identified significant disruptions in key metabolic pathways involved in energy production and amino acid synthesis in T2D rats compared to controls. Notably, aconitic acid, ornithine, and glycine levels were elevated in non-diabetic conditions, whereas phosphoenolpyruvate was markedly increased under T2D conditions. Secondary harmonic generation (SHG) imaging further demonstrated impaired collagen organization within T2D regenerating tissue, correlating with disrupted collagen synthesis critical for bone matrix formation. In vitro, the exogenous supplementation of alpha-ketoglutarate (α-KG)-a crucial citric acid cycle intermediate-enhanced mineralized tissue formation in human adipose-derived mesenchymal stem cells (hAdMSCs) from T2D donors, achieving levels superior to non-T2D cells. These findings underscore the metabolic underpinnings of impaired bone regeneration in T2D. Optimized 3D printed scaffolds alone do not counterbalance the impaired regeneration in T2D. Here we highlight a therapeutic potential of metabolic supplementation to optimize SGBR outcomes. This study provides a critical foundation for advancing translational research and developing regenerative therapies tailored to high-risk metabolic disease populations. STATEMENT OF SIGNIFICANCE: Scaffold-guided bone regeneration (SGBR) holds great promise for addressing large bone defects, but its efficacy in metabolically challenged conditions like Type 2 Diabetes (T2D) remains limited. This study uses a metabolomics-driven approach to reveal how metabolic dysregulation in T2D, including disruptions in energy and amino acid pathways, impairs collagen organization and extracellular matrix (ECM) formation-critical for successful bone healing. By identifying α-ketoglutarate (α-KG) as a potential supplement to restore metabolic balance, this work offers novel insights into enhancing scaffold performance under compromised conditions. These findings provide a foundation for integrating bioactive compounds into scaffold designs, advancing personalized strategies in regenerative medicine, and addressing a critical gap in bone defect treatment for diabetic patients.

Osteochondrosis in horses: An overview of genetic and other factors

Osteochondrosis (OC) is a frequent manifestation of developmental orthopaedic disease, and its severe clinical presentation is known as OC dissecans (OCD). OC is defined as a disruption of the endochondral ossification process in the epiphyseal cartilage, and this disease has been reported in different mammalian species, including humans, dogs, pigs, and horses. OCD is an important cause of lameness in sport horses and is a common cause of impaired orthopaedic potential, whose clinical signs may be of minimal magnitude or manifest as severe joint effusion or clinically noticeable lameness. The aetiology of OCD is unknown, although it has traditionally been considered to be multifactorial. In addition to genetic factors, associated factors include both non-genetic elements such as rapid growth, nutrition, trauma, anatomical conformation, and biomechanics. Since the prevalence of the disease varies greatly depending on the horse breed, from 13% in Swedish Warmblood to 53% in Lusitano breed, genetic factors have a great relevance in the appearance and development of OCD in horses. Many genetic modifications have been related, and the genes involved can be grouped into five clusters, related to fundamental functions for the correct development and regeneration of cartilage, such as collagen, laminin, cell signalling, matrix turnover, and transcriptional regulation. Changes in genes such as COL3A1, COL5A1, COL5A2, COL24A1, COL27A1 (collagen cluster), LAMB1 (laminin cluster), PTH, PHT receptors, and IHH (cell signalling), and genes encoding matrix metalloproteinases have been related to the occurrence and severity of diseases in different equine breeds. This review summarises the main factors associated with OC in horses, with particular emphasis on genetic factors.

Genkwanin blocks the interaction between phosphorylated JNK and NFATc1 to promote osteogenic differentiation and collagen Ⅰ α1 production

Genkwanin (GWA), a flavonoid compound found abundantly in various traditional Chinese medicines, has demonstrated pharmacological effectiveness against a range of diseases. However, its role in bone formation and the underlying mechanisms remain to be elucidated. The aim of this study is to investigate the effects of GWA on osteogenic differentiation and to uncover the possible mechanisms. Primary bone marrow-derived mesenchymal stem cells (BMSCs) and MC3T3-E1 cells induced for osteogenic differentiation were used as in vitro cell models. An ovariectomy (OVX) mouse model to induce secondary osteoporosis was used to evaluate the in vivo pharmacologic efficacy of GWA. Our studies revealed that GWA facilitated osteogenic differentiation and bio-mineralization of BMSCs and MC3T3-E1 cells in vitro, and could effectively prevent OVX-induced systematic bone loss and collagen Ⅰ α1 (COL1A1) reduction in vivo. Mechanism studies indicated that GWA could directly bind to phosphorylated c-Jun N-terminal kinase (pJNK) to prevent the phosphorylation of nuclear factor of activated T cells 1 (NFATc1) by JNK, thereby promote osteogenic differentiation and COL1A1 production via increasing the nuclear localization of NFATc1. This is distinct from the previously recognized function of the JNK/AP-1/NFATc1 signaling pathway in activating osteoclast differentiation. More importantly, GWA had no significant effects on estrogen-related signaling pathways, indicating a unique advantage in lowering the risk of gynecological cancer. In conclusion, our data suggest that GWA may be a promising candidate for the therapy of diseases associated with bone loss. Targeting pJNK-NFATc1 interaction may represent a new strategy to stimulate osteogenesis.

A Study of the Effects of Oleuropein and Polydatin Association on Muscle and Bone Metabolism

Sarcopenia and osteoporosis are age-related musculoskeletal pathologies that often develop in parallel, and numerous studies support the concept of a bone-muscle unit, where deep interaction between the two tissues takes place. In Mediterranean areas, the lowest incidence of osteoporosis within Europe is observed, so the Mediterranean diet was suggested to play an important role. Consequently, in this study, oleuropein, a phenolic compound found in olive oil, and polydatin, another natural polyphenol found in the Mediterranean diet, were evaluated to determine their beneficial effects on bone and muscle metabolism. In human osteoblasts and skeletal muscle myoblasts, the effects were examined, and, after analyzing the cytotoxic effect to find non-toxic doses, the modulation of bone and muscle differentiation markers was evaluated at the gene and protein levels using PCR, Western blot, and immunohistochemistry. Interestingly, the compounds increased markers involved in osteoblast differentiation, such as osteocalcin, type I collagen, and dentin-sialo-phosphoprotein, as well as markers involved in myoblast differentiation, such as myogenic regulatory factors and creatine kinase. These effects were most noticeable when the compounds were administered together. These results suggest a beneficial role for oleuropein-polydatin association on bone and muscle tissue pathologies simultaneously.

Therapeutic Potential of Exercise-Induced SPARC in Bone Health?

Exploring biological properties leading to potential pharmacological applications has been a fruitful approach in biomedical research. Secreted protein acidic and rich in cysteine (SPARC) is an exercise-induced glycoprotein known for its functions at different cellular and molecular levels. Among the properties it has, its calcium and collagen binding patterns along with other biochemical, metabolic, and structural effects represent a starting point towards developing therapeutic options based on SPARC properties for bones in pathological, preventive, and regenerative contexts. Such properties can be explored in conditions including bone fractures or requiring bone regenerative adjuvants. In addition, these properties can also be applied in basic research such as building an environment more suitable for cellular proliferation or optimizing in vitro conditions.

Naringin promotes osteoblast differentiation and ameliorates osteoporosis in ovariectomized mice

This study aimed to investigate the anti-osteoporotic mechanisms of naringin in osteoblasts and mice. In vitro, MC3T3-E1 cells were treated with naringin to detect cell proliferation, alkaline phosphatase (ALP) activity, and calcified nodule formation. Western blot was used to analyze the expression of osteogenic markers (OPN, COL1A1, RUNX2) and Wnt/β-catenin pathway proteins (Wnt3a, β-catenin). In vivo, ovariectomized (OVX) mice were treated with naringin for 3 months to observe bone microstructure, femoral histomorphology, and marker expression. Results showed that 0.1, 0.5, and 1 µmol/L naringin significantly promoted cell proliferation, enhanced ALP activity, and increased calcified nodule formation. Naringin also improved bone mineral density (BMD) and trabecular bone number in OVX mice. It elevated serum levels of bone formation markers (P1NP, OCN) while reducing the bone resorption marker CTX-1. Both in vitro and in vivo, naringin upregulated OPN, COL1A1, RUNX2, Wnt3a, and β-catenin expression, and induced β-catenin nuclear translocation. Notably, naringin antagonized the inhibitory effects of XAV939 (a Wnt/β-catenin pathway inhibitor) on OPN, COL1A1, and RUNX2 protein expression. These findings demonstrate that naringin enhances bone density in OVX mice and promotes osteogenic differentiation of MC3T3-E1 cells via activation of the Wnt/β-catenin pathway.

The proteome of osteoblasts in a 3D culture perfusion bioreactor model compared with static conditions

Bone disorders represent a significant global burden. Currently, animal models are used to develop and screen novel treatments. However, interspecies variations and ethical concerns highlight the need for a more complex 3D bone model. In this study, we developed a simplified in vitro bone-like model using a U-CUP perfusion-based bioreactor system, designed to provide continuous nutrient flow and mechanostimulation through 3D cultures. An immortalized human fetal osteoblastic cell line was seeded on collagen scaffolds and cultured for 21 days in both a perfusion bioreactor system and in static cultures. PrestoBlue™ assay, scanning electron microscopy, and proteomics allowed monitoring of metabolic activity and compared morphological and proteome differences between both conditions. Results indicated an altered cellular morphology in the bioreactor compared to the static cultures and identified a total of 3494 proteins. Of these, 105 proteins exhibited significant upregulation in the static culture, while 86 proteins displayed significant downregulation. Enrichment analyses of these proteins revealed ten significant pathways including epithelial-mesenchymal transition, TNF-alpha signaling via NF-kB, and KRAS pathway. The current data indicated of osteogenic differentiation enhancement within the bioreactor on day 21 compared to static cultures. In conclusion, the U-CUP perfusion bioreactor is beneficial for facilitating osteogenic differentiation in 3D cultures.

Phytol-mixed micelles alleviate dexamethasone-induced osteoporosis in zebrafish: Activation of the MMP3-OPN-MAPK pathway-mediating bone remodeling

This research investigates the therapeutic efficacy of phytol-mixed micelles in mitigating dexamethasone (Dex)-induced osteoporosis in zebrafish, with a particular focus on scale regeneration. Osteoporosis was induced in zebrafish through exposure to Dex, and the effects of phytol-mixed micelles were evaluated in this model. Following phytol therapy, bone mineralization was assessed using calcium, phosphorus, and alizarin red staining tests. Additionally, commercially available kits quantified the levels of tartrate-resistant acid phosphatase (TRAP), hydroxyproline (HP), and alkaline phosphatase (ALP). The mRNA expression levels of MMP3, osteopontin (OPN), and mitogen-activated protein kinase (MAPK) were examined using reverse transcription polymerase chain reaction (RT-PCR). The findings indicated that phytol significantly increased calcium and phosphorus concentrations. Phytol-mixed micelle therapy led to increased calcium deposition and enhanced bone formation, as evidenced by alizarin red staining. Moreover, phytol administration resulted in increased HP content and upregulated ALP and TRAP activities in zebrafish. RT-PCR tests demonstrated that phytol plays a role in the restoration of the MMP3-OPN-MAPK pathway. In summary, this research highlights the potential of phytol-mixed micelles in ameliorating Dex-induced osteoporosis in zebrafish. Clarifying phytol's mechanism, particularly its stimulation of the MMP3-OPN-MAPK pathway, provides insight into its role in facilitating bone remodeling.

Advances in Molecular Function and Recombinant Expression of Human Collagen

Collagen is the main protein found in skin, bone, cartilage, ligaments, tendons and connective tissue, and it can exhibit properties ranging from compliant to rigid or form gradients between these states. The collagen family comprises 28 members, each containing at least one triple-helical domain. These proteins play critical roles in maintaining mechanical characteristics, tissue organization, and structural integrity. Collagens regulate cellular processes such as proliferation, migration, and differentiation through interactions with cell surface receptors. Fibrillar collagens, the most abundant extracellular matrix (ECM) proteins, provide organs and tissues with structural stability and connectivity. In the mammalian myocardial interstitium, types I and III collagens are predominant: collagen I is found in organs, tendons, and bones; collagen II is found in cartilage; collagen III is found in reticular fibers; collagen IV is found in basement membranes; and collagen V is found in nails and hair. Recombinant human collagens, particularly in sponge-like porous formats combined with bone morphogenetic proteins, serve as effective scaffolds for bone repair. Due to their biocompatibility and low immunogenicity, collagens are pivotal in tissue engineering applications for skin, bone, and wound regeneration. Recombinant technology enables the production of triple-helical collagens with amino acid sequences identical to human tissue-derived collagens. This review summarizes recent advances in the molecular functions and recombinant expression of human collagens, with a focus on their biomedical applications.

A newly designed Flexible Hydrated-Hardening Bone Graft (FHBG) promotes bone regeneration and in vivo calvarial repair

BACKGROUND

Autologous bone remains the gold standard for surgical bone reconstruction but presents clinical challenges like donor site complications and operational difficulties.

METHOD

We investigate the osteogenic effects of a newly designed, ceramic and collagen-based, submicron-processed Flexible Hydrated-Hardening Bone Graft (FHBG), using both murine and human mesenchymal stem cells. We also compare the efficacy and safety of FHBG with a commercially available (CA) graft in New Zealand white rabbits with cranial bone defects. Rabbits were divided into three groups: no graft, CA, and FHBG, and evaluated using Micro-CT and histological analysis at three and six weeks post-surgery. Safety was assessed through blood samples.

RESULTS

In vitro, FHBG promoted osteogenesis and upregulated osteogenic-associated genes in mesenchymal stem cells. In vivo, FHBG significantly enhanced bone regeneration, showing approximately 25% and 30% more improvement than the control at three and six weeks post-surgery. FHBG also had about half the residual content compared to the CA group. Blood analysis showed no hepatotoxicity or nephrotoxicity associated with the graft.

CONCLUSION

FHBG significantly promotes bone regeneration both in vitro and in vivo. Additionally, FHBG has been demonstrated to be safe, with fewer residuals remaining in the body compared to currently in-use clinical bone grafts. This study validates the ability of the newly designed FHBG to facilitate osteogenesis in vitro and demonstrates its efficacy and safety in new bone formation in vivo. The lower residual material further suggests a reduced long-term impact and associated risk with the graft.

Bioactive Carbon Dots from Clove Residue: Synthesis, Characterization, and Osteogenic Properties

Background/Objectives: Bone regeneration using nanomaterial-based approaches shows promise for treating critical bone defects. However, developing sustainable and cost-effective therapeutic materials remains challenging. This study investigates the osteogenic potential of clove-derived carbon dots (C-CDs) for bone regeneration applications. Methods: C-CDs were synthesized using a green hydrothermal method. The osteogenic potential was evaluated in human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and validated using ectopic bone formation and calvarial defect models. Results: C-CDs demonstrated uniform morphology (~10 nm) with efficient cellular uptake. In vitro studies showed successful osteogenic differentiation through the upregulation of RUNX2, ALP, COL1A1, and BMP-2 mediated by Wnt/β-catenin/GSK3β and BMP signaling pathways. In vivo models have also demonstrated that C-CDs are effective in promoting bone regeneration. Conclusions: These findings establish C-CDs as promising candidates for bone regeneration therapy, offering a sustainable alternative to current treatments. While optimization is needed, their demonstrated osteogenic properties warrant further development for regenerative medicine applications.

Silk fibroin thermosensitive polymers: Osteogenic, anti-inflammatory, and angiogenic effects for osteomyelitis treatment

Infectious bone defects pose a significant challenge in orthopedics by hindering healing and vascularization. This study explored the impact of fibroin thermosensitive hydrogel on osteogenesis, inflammatory response, and angiogenesis as a potential biomaterial for bone regeneration in osteomyelitis treatment. The biocompatibility of the hydrogel by live/dead staining revealed a high number of viable osteoblast cells after 14 days. ALP activity was significantly increased in all hydrogel formulations, with F3 showing the highest levels of total protein content and calcium deposition, indicating more effective osteogenesis. Gene expression analysis of the osteogenesis-related genes demonstrated that RUNX2 was upregulated by day 7, followed by increased expressions of the OCN and COL-1 genes at later stages. The inflammatory response to F3 was assessed by measuring the nitric oxide (NO) production and pro-inflammatory gene expression in LPS-stimulated RAW 264.7 macrophages. The F3 formulation significantly reduced NO production and iNOS expression, suggesting selective inhibition of the inflammatory pathway. The VEGF-loaded F3 formulation exhibited substantial angiogenic potential, enhancing HUVEC cell proliferation by 140% over 48 h. The osteogenic, anti-inflammatory, and angiogenic effects shown by the F3 formulation were well-suited for applications in osteomyelitis treatment.

The facilitated osteogenic differentiation by extracellular proline treatment in in vitro cell cultivation using MC3T3E1 and hPDLF

Proline is a major substrate in collagen biosynthesis and is required for collagen molecule formations. However, detailed explanations of the molecular basis through which proline functions in collagen biosynthesis have yet to be provided. Thus, genome-wide screening was employed to elucidate these in the pre-osteoblastic MC3T3-E1 and human periodontal ligament fibroblast (hPDLF) cell lines. Indeed, both cell lines represent important sources for collagen biosynthesis and tissue regeneration in the dental region, specifically treating extracellular proline during cultivations. The altered gene expression patterns were identified, and the precise expression patterns were confirmed by microarray. Cell viability and osteogenic differentiation patterns were examined using a range of experimental methods, such as the MTS assay, ALP staining, ARS staining, and collagen (COL)-type1A ELISA. Overall, we revealed a cell line-specific function of exogenous proline in collagen biosynthesis during osteogenic differentiation conditions with the candidate signaling pathways. These putative signaling networks could represent plausible answers to understanding collagen biosynthesis for regenerating connective tissues such as skin, muscle, and bone.

Advances in green carbon-based biosorbents: From conventional to miniaturized sample preparation strategies

Developing novel sorbent phases has advanced solid-based sample preparation techniques, improving analytical performance in complex matrices. Carbon-based sorbents, known for their high surface area, thermal and mechanical stability, and modifiability due to abundant organic functional groups, have emerged as exceptional materials in this field. Due to their versatile characteristics, carbon-based materials have been extensively investigated as promising materials for anchoring and functionalization with biopolymers, resulting in innovative hybrid materials, so-called carbon-based biosorbents. These biosorbents offer numerous advantages, including enhanced physicochemical properties and biodegradability, which help reduce the environmental impact of their synthesis, particularly when compared to conventional synthetic sorbent production methods that lack adherence to environmentally sustainable protocols. Among the various biopolymers used for modification, chitosan, starch, cyclodextrin, cellulose, and agarose have been identified as promising candidates for integration with carbon-based materials. In light of the ongoing advancements in developing novel carbon-based biosorbent materials, this review aims to highlight their synthesis using these biopolymers and examine their application in conventional and miniaturized sample preparation techniques across diverse matrices.

Dose-dependent enhancement of in vitro osteogenic activity on strontium-decorated polyetheretherketone

Polyetheretherketone (PEEK) is widely used in orthopedic and dental implants due to its excellent mechanical properties, chemical stability, and biocompatibility. However, its inherently bioinert nature makes it present weak osteogenic activity, which greatly restricts its clinical adoption. Herein, strontium (Sr) is incorporated onto the surface of PEEK using mussel-inspired polydopamine coating to improve its osteogenic activity. X-ray photoelectron spectroscopy and ion release assay results confirm that different concentrations of Sr are incorporated onto the PEEK substrate surfaces. The strontium-modified PEEK samples show a stable Sr ion release in 35 days of detection. Better results of MC3T3-E1 pre-osteoblasts adhesion, spreading, and proliferation can be observed in strontium-modified PEEK groups, which demonstrates strontium-modified PEEK samples with the improved MC3T3-E1 pre-osteoblasts compatibility. The boosted osteogenic activity of strontium-modified PEEK samples has been demonstrated by the better performed of ALP activity, extracellular matrix mineralization, collagen secretion, and the remarkable up-regulation of ALP, OCN, OPN, Runx2, Col-I, BSP, and OSX of the MC3T3-E1 pre-osteoblasts. Additionally, the strontium-modified PEEK samples exhibit a dose-dependent enhancement of osteoblasts compatibility and osteogenic activity, and the PEEK-Sr10 group shows the best. These findings indicate that strontium-decorated PEEK implants show promising application in orthopedic and dental implants.

Application of collagen in bone regeneration

At present, there is a significant population of individuals experiencing bone deficiencies caused by injuries, ailments affecting the bones, congenital abnormalities, and cancer. The management of substantial bone defects a significant global orthopedic challenge due to the intricacies involved in promoting and restoring the growth of fresh osseous tissue. Autografts are widely regarded as the "gold standard" for repairing bone defects because of their superior tissue acceptance and ability to control osteogenesis. However, patients undergoing autografts may encounter various challenges, including but not limited to hernia, bleeding, nerve impairment, tissue death. Therefore, researchers in regenerative medicine are striving to find alternatives. Collagen is the most abundant protein in the human body, and its triple helix structure gives it unique characteristics that contribute to its strength and functionality in various tissues. Collagen is commonly processed into various forms such as scaffolds, sponges, membranes, hydrogels, and composite materials, due to its unique compatibility with the human body, affinity for water, minimal potential for immune reactions, adaptability, and ability to transport nutrients or drugs. As an alternative material in the field of bone regeneration, collagen is becoming increasingly important. The objective of this review is to provide a comprehensive analysis of the primary types and sources of collagen, their processes of synthesis and degradation, as well as the advancements made in bone regeneration research and its potential applications. A comprehensive investigation into the role of collagen in bone regeneration is undertaken, providing valuable points of reference for a more profound comprehension of collagen applications in this field. The concluding section provides a comprehensive overview of the prospective avenues for collagen research, underscoring their promising future and highlighting their significant potential in the field of bone regeneration. The Translational Potential of this Article. The comprehensive exploration into the diverse functions and translational potential of collagen in bone regeneration, as demonstrated in this review, these findings underscore their promising potential as a treatment option with significant clinical implications, thus paving the way for innovative and efficacious therapeutic strategies in this domain.

Unraveling the Mechanism of Impaired Osteogenic Differentiation in Osteoporosis: Insights from ADRB2 Gene Polymorphism

Osteoporosis is characterized by increased resorption and decreased bone formation; it is predominantly influenced by genetic factors. G-protein coupled receptors (GPCRs) play a vital role in bone homeostasis, and mutations in these genes are associated with osteoporosis. This study aimed to investigate the impact of single nucleotide polymorphism (SNP) rs1042713 in the ADRB2 gene, encoding the beta-2-adrenergic receptor, on osteoblastogenesis. Herein, using quantitative polymerase chain reaction, western immunoblotting, immunofluorescence assays, and flow cytometry, we examined the expression of ADRB2 and markers of bone matrix synthesis in mesenchymal stem cells (MSCs) derived from osteoporosis patient (OP-MSCs) carrying ADRB2 SNP in comparison with MSCs from healthy donor (HD-MSCs). The results showed significantly reduced ADRB2 expression in OP-MSCs at both the mRNA and protein levels, alongside decreased type 1 collagen expression, a key bone matrix component. Notably, OP-MSCs exhibited increased ERK kinase expression during differentiation, indicating sustained cell cycle progression, unlike that going to HD-MSC. These results provide novel insights into the association of ADRB2 gene polymorphisms with osteogenic differentiation. The preserved proliferative activity of OP-MSCs with rs1042713 in ADRB2 contributes to their inability to undergo effective osteogenic differentiation. This research suggests that targeting genetic factors may offer new therapeutic strategies to mitigate osteoporosis progression.

Integrated Transcriptomic and Proteomic Analyses of Antler Growth and Ossification Mechanisms

Antlers are the sole mammalian organs capable of continuous regeneration. This distinctive feature has evolved into various biomedical models. Research on mechanisms of antler growth, development, and ossification provides valuable insights for limb regeneration, cartilage-related diseases, and cancer mechanisms. Here, ribonucleic acid sequencing (RNA-seq) and four-dimensional data-independent acquisition (4D DIA) technologies were employed to examine gene and protein expression differences among four tissue layers of the Chinese milu deer antler: reserve mesenchyme (RM), precartilage (PC), transition zone (TZ), cartilage (CA). Overall, 4611 differentially expressed genes (DEGs) and 2388 differentially expressed proteins (DEPs) were identified in the transcriptome and proteome, respectively. Among the 828 DEGs common to both omics approaches, genes from the collagen, integrin, and solute carrier families, and signaling molecules were emphasized for their roles in the regulation of antler growth, development, and ossification. Bioinformatics analysis revealed that in addition to being regulated by vascular and nerve regeneration pathways, antler growth and development are significantly influenced by numerous cancer-related signaling pathways. This indicates that antler growth mechanisms may be similar to those of cancer cell proliferation and development. This study lays a foundation for future research on the mechanisms underlying the rapid growth and ossification of antlers.

Fitness landscapes of human microsatellites

Advances in DNA sequencing technology and computation now enable genome-wide scans for natural selection to be conducted on unprecedented scales. By examining patterns of sequence variation among individuals, biologists are identifying genes and variants that affect fitness. Despite this progress, most population genetic methods for characterizing selection assume that variants mutate in a simple manner and at a low rate. Because these assumptions are violated by repetitive sequences, selection remains uncharacterized for an appreciable percentage of the genome. To meet this challenge, we focus on microsatellites, repetitive variants that mutate orders of magnitude faster than single nucleotide variants, can harbor substantial variation, and are known to influence biological function in some cases. We introduce four general models of natural selection that are each characterized by just two parameters, are easily simulated, and are specifically designed for microsatellites. Using a random forests approach to approximate Bayesian computation, we fit these models to carefully chosen microsatellites genotyped in 200 humans from a diverse collection of eight populations. Altogether, we reconstruct detailed fitness landscapes for 43 microsatellites we classify as targets of selection. Microsatellite fitness surfaces are diverse, including a range of selection strengths, contributions from dominance, and variation in the number and size of optimal alleles. Microsatellites that are subject to selection include loci known to cause trinucleotide expansion disorders and modulate gene expression, as well as intergenic loci with no obvious function. The heterogeneity in fitness landscapes we report suggests that genome-scale analyses like those used to assess selection targeting single nucleotide variants run the risk of oversimplifying the evolutionary dynamics of microsatellites. Moreover, our fitness landscapes provide a valuable visualization of the selective dynamics navigated by microsatellites.

Thermoresponsive and Supramolecular Polymers: Interesting Biomaterials for Drug Delivery

How to use and deliver drugs to diseased and damaged areas has been one of the main concerns of pharmacologists and doctors for a long time. With the efforts of researchers, the advancement of technology, and the involvement of engineering in the health field, diverse and promising approaches have been studied and used to achieve this goal. A better understanding of biomaterials and the ability of production equipment led researchers to offer new drug delivery systems to the world. In recent decades, responsive polymers (exclusively to temperature and pH) and supramolecular polymers have received much attention due to their unique capabilities. Although this field of research still needs to be scrutinized and studied more, their recognition, examination, and use as drug delivery systems is a start for a promising future. This review study, focusing on temperature-responsive and supramolecular biomaterials and their application as drug delivery systems, deals with their structure, properties, and role in the noninvasive and effective delivery of medicinal agents.

From gut to bone: deciphering the impact of gut microbiota on osteoporosis pathogenesis and management

Osteoporosis (OP) is characterized by decreased bone mineral density (BMD) and increased fracture risk, poses a significant global health burden. Recent research has shed light on the bidirectional relationship between gut microbiota (GM) and bone health, presenting a novel avenue for understanding OP pathogenesis and developing targeted therapeutic interventions. This review provides a comprehensive overview of the GM-bone axis, exploring the impact of GM on OP development and management. We elucidate established risk factors and pathogenesis of OP, delve into the diversity and functional changes of GM in OP. Furthermore, we examine experimental evidence and clinical observations linking alterations in GM composition or function with variations in BMD and fracture risk. Mechanistic insights into microbial mediators of bone health, such as microbial metabolites and products, are discussed. Therapeutic implications, including GM-targeted interventions and dietary strategies, are also explored. Finally, we identify future research directions and challenges in translating these findings into clinical practice.

Hyaluronidase inhibits TGF-β-mediated rat periodontal ligament fibroblast expression of collagen and myofibroblast markers: An in vitro exploration of periodontal tissue remodeling

OBJECTIVE

To determine the effect of hyaluronic acid (HA) degradation by hyaluronidase (HYAL) in inhibiting collagen fiber production by rat periodontal ligament cells (rPDLCs).

DESIGN

Primary rPDLCs were isolated from the euthanized rats and used for in vitro experiments. The appropriate HYAL concentration was determined through CCK-8 testing for cytotoxicity detection and Alizarin red staining for mineralization detection. RT-qPCR and western blot assays were conducted to assess the effect of HYAL, with or without TGF-β, on generation of collagen fiber constituents and expression of actin alpha 2, smooth muscle (ACTA2) of rPDLCs.

RESULTS

Neither cell proliferation nor mineralization were significantly affected by treatment with 4 U/mL HYAL. HYAL (4 U/mL) alone downregulated type I collagen fiber (Col1a1 and Col1a2) and Acta2 mRNA expression; however, ACTA2 and COL1 protein levels were only downregulated by HYAL treatment after TGF-β induction.

CONCLUSIONS

Treatment of rPDLCs with HYAL can inhibit TGF-β-induced collagen matrix formation and myofibroblast transformation.

Assessment of inflammatory suppression and fibroblast infiltration in tissue remodelling by supercritical CO2 acellular dermal matrix (scADM) utilizing Sprague Dawley models

Human skin-derived ECM aids cell functions but can trigger immune reactions; therefore it is addressed through decellularization. Acellular dermal matrices (ADMs), known for their regenerative properties, are used in tissue and organ regeneration. ADMs now play a key role in plastic and reconstructive surgery, enhancing aesthetics and reducing capsular contracture risk. Innovative decellularization with supercritical carbon dioxide preserves ECM quality for clinical use. The study investigated the cytotoxicity, biocompatibility, and anti-inflammatory properties of supercritical CO2 acellular dermal matrix (scADM) in vivo based on Sprague Dawley rat models. Initial experiments in vitro with fibroblast cells confirmed the non-toxic nature of scADM and demonstrated cell infiltration into scADMs after incubation. Subsequent tests in vitro revealed the ability of scADM to suppress inflammation induced by lipopolysaccharides (LPS) presenting by the reduction of pro-inflammatory cytokines TNF-α, IL-6, IL-1β, and MCP-1. In the in vivo model, histological assessment of implanted scADMs in 6 months revealed a decrease in inflammatory cells, confirmed further by the biomarkers of inflammation in immunofluorescence staining. Besides, an increase in fibroblast infiltration and collagen formation was observed in histological staining, which was supported by various biomarkers of fibroblasts. Moreover, the study demonstrated vascularization and macrophage polarization, depicting increased endothelial cell formation. Alteration of matrix metalloproteinases (MMPs) was analyzed by RT-PCR, indicating the reduction of MMP2, MMP3, and MMP9 levels over time. Simultaneously, an increase in collagen deposition of collagen I and collagen III was observed, verified in immunofluorescent staining, RT-PCR, and western blotting. Overall, the findings suggested that scADMs offer significant benefits in improving outcomes in implant-based procedures as well as soft tissue substitution.