Decellularized periosteum and sodium alginate-based photoresponsive dressing with copper selenide nanoparticles for infected-wound healing in diabetic mice.

Diabetes-related skin ulcers are of significant clinical concern. Although conventional dressings have been developed, their outcomes have not been adequate, indicating the need to investigate functional dressings for the treatment of diabetic ulcers. Copper selenide nanoparticles (Cu2Se NPs) demonstrate outstanding photoresponsiveness, which is critical to the healing process. However, their limited solubility in water restricts their application. To synthesize the ODT-PMMA@Cu2Se NP-doped decellularized periosteum­sodium alginate functional dressing-ODT-PMMA@Cu2Se/ECM-S (OP@Cu2Se/ECM-S), Cu2Se NPs were modified by n-octadecanethiol (ODT) end-functionalized poly (methacrylic acid) (PMAA) ligands homogeneously dispersed in a decellularized periosteum/sodium alginate matrix. This process improved the water solubility and stability. Moreover, under near-infrared irradiation (NIR), ODT-PMMA@Cu2Se demonstrated robust photo-responsiveness along with photothermal and photodynamic effects, leading to rapid heating and stimulation of reactive oxygen species (ROS) generation. These two processes work in concert to exhibit excellent antibacterial ability; at 20 µg/mL concentration of Cu2Se NPs, the bacterial activities of S. aureus and E. coli were 5.40 % and 0.96 %, respectively. Without the NIR laser irradiation, OP@Cu2Se/ECM-S rapidly increased the vascular endothelial growth factor (VEGF) expression, triggered the phosphatidylinositide 3-kinases (PI3K) and protein kinase B (AKT) signaling pathway, affected the expression of bFGF and CD31, and promoted neovascularization, proliferation, and cell migration. In a diabetic mouse wound model, OP@Cu2Se/ECM-S exhibited good biocompatibility and promoted epidermal regeneration, collagen deposition, and neovascularization. In a mouse model of subcutaneous abscesses, OP@Cu2Se/ECM-S also showed excellent antibacterial activity, in vivo experiments confirmed a decrease in bacterial activity to 1.97 %. Thus, OP@Cu2Se/ECM-S is a potentially useful approach for healing diabetic wounds.

Electrospun Biomimetic Periosteum Capable of Controlled Release of Multiple Agents for Programmed Promoting Bone Regeneration.

The effective repair of large bone defects remains a major challenge due to its limited self-healing capacity. Inspired by the structure and function of the natural periosteum, an electrospun biomimetic periosteum is constructed to programmatically promote bone regeneration using natural bone healing mechanisms. The biomimetic periosteum is composed of a bilayer with an asymmetric structure in which an aligned electrospun poly(ε-caprolactone)/gelatin/deferoxamine (PCL/GEL/DFO) layer mimics the outer fibrous layer of the periosteum, while a random coaxial electrospun PCL/GEL/aspirin (ASP) shell and PCL/silicon nanoparticles (SiNPs) core layer mimics the inner cambial layer. The bilayer controls the release of ASP, DFO, and SiNPs to precisely regulate the inflammatory, angiogenic, and osteogenic phases of bone repair. The random coaxial inner layer can effectively antioxidize, promoting cell recruitment, proliferation, differentiation, and mineralization, while the aligned outer layer can promote angiogenesis and prevent fibroblast infiltration. In particular, different stages of bone repair are modulated in a rat skull defect model to achieve faster and better bone regeneration. The proposed biomimetic periosteum is expected to be a promising candidate for bone defect healing.

Mechanical Properties of Human Concentrated Growth Factor (CGF) Membrane and the CGF Graft with Bone Morphogenetic Protein-2 (BMP-2) onto Periosteum of the Skull of Nude Mice.

Concentrated growth factor (CGF) is 100% blood-derived, cross-linked fibrin glue with platelets and growth factors. Human CGF clot is transformed into membrane by a compression device, which has been widely used clinically. However, the mechanical properties of the CGF membranes have not been well characterized. The aims of this study were to measure the tensile strength of human CGF membrane and observe its behavior as a scaffold of BMP-2 in ectopic site over the skull. The tensile test of the full length was performed at the speed of 2mm/min. The CGF membrane (5 × 5 × 2 mm3) or the CGF/BMP-2 (1.0 µg) membrane was grafted onto the skull periosteum of nude mice (5-week-old, male), and harvested at 14 days after the graft. The appearance and size of the CGF membranes were almost same for 7 days by soaking at 4 °C in saline. The average values of the tensile strength at 0 day and 7 days were 0.24 MPa and 0.26 MPa, respectively. No significant differences of both the tensile strength and the elastic modulus were found among 0, 1, 3, and 7 days. Supra-periosteal bone induction was found at 14 days in the CGF/BMP-2, while the CGF alone did not induce bone. These results demonstrated that human CGF membrane could become a short-term, sticky fibrin scaffold for BMP-2, and might be preserved as auto-membranes for wound protection after the surgery.

Bioactive Glass Fiber-Reinforced Plastic Composites Prompt a Crystallographic Lophelia Atoll-Like Skeletal Microarchitecture Actuating Periosteal Cambium.

The touchstone for bone replacing or anchoring trauma implants, besides resorption, includes functional ankylosis at a fixation point and replacement by viable functional neo-bone tissues. These parameters redefined the concept of "resorbability" as "bioresorbability." Interference screws are the most commonly used resorbable anchoring implants for anterior cruciate ligament (ACL) reconstruction (surgery). Over the years, the bioresorbable screw fixation armamentarium has amplified countless choices, but instability and postimplantation complications have raised concerns about its reliability and efficacy. Owing to this interest, in this work, bioactive glass fiber-reinforced plastic (BGFP) composites with (BGFPnb5) and without (BGFP5) niobicoxide composing multiplexed network modifiers are reported as bioresorbable bone-anchoring substitutes. These synergistically designed composites have a fabricated structure of continuous, unidirectional BG fibers reinforced in an epoxy resin matrix using "melt-drawing and microfabrication" technology. The BGFP microarchitecture is comprised of multiplexed oxide components that influence bioactive response in a distinctive lophelia atoll-like apatite formation. Furthermore, it assists in the proliferation, adherence, and migration of bone marrow-derived mesenchymal stem cells. It also exhibits superior physicochemical characteristics such as surface roughness, hydrophilic exposure, distinctive flexural strength, and bioresorption. Thus, it induces restorative bone osseointegration and osteoconduction and actuates periosteum function. In addition, the BGFP influences the reduction of DH5-α Escherichia coli in suspension culture, demonstrating potential antibacterial efficacy. In conclusion, the BGFP composite therapeutic efficacy demonstrates distinctive material characteristics aiding in bone regeneration and restoration that could serve as a pioneer in orthopedic regenerative medicine.

Toxicity of tranexamic acid (TXA) to intra-articular tissue in orthopaedic surgery: a scoping review.

PURPOSE: Intra-articular administration of tranexamic acid (TXA) in orthopaedic arthroplasty and arthroscopic procedures has become increasingly common over the past decade. However, several recent reports have shown that TXA has the potential to be cytotoxic to cartilage, tendon and synovium. Our aim was to review the literature for evidence of toxic effects from TXA exposure to intra-articular tissue. METHODS: A scoping review methodology was used to search for studies assessing the toxic effects of TXA exposure to intra-articular tissues. MEDLINE, EMBASE, SCOPUS and The Cochrane Library were searched. Relevant information was extracted and synthesis of the retrieved data followed a basic content analytical approach. RESULTS: A total of 15 laboratory studies were retrieved. No clinical studies reporting a toxic effect of TXA on intra-articular tissue were identified in our search. Studies were analysed according to species of origin, tissue of origin and study setting (in vitro, ex vivo, or in vivo). There was increasing cytotoxicity to chondrocytes, tenocytes, synoviocytes and periosteum-derived cells with TXA concentrations beyond 20 mg/ml. Monolayer cell cultures appear more susceptible to TXA exposure, than three-dimensional and explant culture models. In vivo studies have not demonstrated a major toxic effect. CONCLUSIONS: Current evidence suggests a dose-dependent toxic effect on cartilage, tendon, and synovial tissue. Concentrations of 20 mg/ml or less are expected to be safe. There is a significant body of evidence to suggest the need for caution with intraarticular administration of TXA. There is a need for further human clinical trials in order to clarify the long-term safety of TXA topical application.

Sodium Alginate as a Potential Therapeutic Filler: An In Vivo Study in Rats.

Filler injection demand is increasing worldwide, but no ideal filler with safety and longevity currently exists. Sodium alginate (SA) is the sodium salt of alginic acid, which is a polymeric polysaccharide obtained by linear polymerization of two types of uronic acid, d-mannuronic acid (M) and l-guluronic acid (G). This study aimed to evaluate the therapeutic value of SA. Nine SA types with different M/G ratios and viscosities were tested and compared with a commercially available sodium hyaluronate (SH) filler. Three injection modes (onto the periosteum, intradermally, or subcutaneously) were used in six rats for each substance, and the animals were sacrificed at 4 or 24 weeks. Changes in the diameter and volume were measured macroscopically and by computed tomography, and histopathological evaluations were performed. SA with a low M/G ratio generally maintained skin uplift. The bulge gradually decreased over time but slightly increased at 4 weeks in some samples. No capsule formation was observed around SA. However, granulomatous reactions, including macrophage recruitment, were observed 4 weeks after SA implantation, although fewer macrophages and granulomatous reactions were observed at 24 weeks. The long-term volumizing effects and degree of granulomatous reactions differed depending on the M/G ratio and viscosity. By contrast, SH showed capsule formation but with minimal granulomatous reactions. The beneficial and adverse effects of SA as a filler differed according to the viscosity or M/G ratio, suggesting a better long-term volumizing effect than SH with relatively low immunogenicity.

Parthenolide Has Negative Effects on In Vitro Enhanced Osteogenic Phenotypes by Inflammatory Cytokine TNF-α via Inhibiting JNK Signaling.

Nuclear factor kappa B (NF-κB) regulates inflammatory gene expression and represents a likely target for novel disease treatment approaches, including skeletal disorders. Several plant-derived sesquiterpene lactones can inhibit the activation of NF-κB. Parthenolide (PTL) is an abundant sesquiterpene lactone, found in Mexican Indian Asteraceae family plants, with reported anti-inflammatory activity, through the inhibition of a common step in the NF-κB activation pathway. This study examined the effects of PTL on the enhanced, in vitro, osteogenic phenotypes of human periosteum-derived cells (hPDCs), mediated by the inflammatory cytokine tumor necrosis factor (TNF)-α. PTL had no significant effects on hPDC viability or osteoblastic activities, whereas TNF-α had positive effects on the in vitro osteoblastic differentiation of hPDCs. c-Jun N-terminal kinase (JNK) signaling played an important role in the enhanced osteoblastic differentiation of TNF-α-treated hPDCs. Treatment with 1 µM PTL did not affect TNF-α-treated hPDCs; however, 5 and 10 µM PTL treatment decreased the histochemical detection and activity of alkaline phosphatase (ALP), alizarin red-positive mineralization, and the expression of ALP and osteocalcin mRNA. JNK phosphorylation decreased significantly in TNF-α-treated hPDCs pretreated with PTL. These results suggested that PTL exerts negative effects on the increased osteoblastic differentiation of TNF-α-treated hPDCs by inhibiting JNK signaling.

Abnormal FDG Uptake on PET/CT Due to Periosteal Reaction Caused by Hypervitaminosis D in a Pediatric Patient.

A 7-year-old boy presented with diffuse bone pain. FDG PET/CT was performed to find the possible underlying malignant cause of hypercalcemia. The images demonstrated multiple foci of abnormal FDG activity at the sites of periosteal reaction. In addition, calcium deposit was noted in the basal ganglia, stomach, and the colon. History taking revealed that the patient had routinely taken an over-the-counter "supplement" that contains a high dose of vitamin D. One week after calcitonin therapy and stopping the supplement, the patient became symptom free. This case suggests that hypervitaminosis D might cause hypermetabolic periosteal reaction on FDG PET/CT imaging.

Resveratrol can enhance osteogenic differentiation and mitochondrial biogenesis from human periosteum-derived mesenchymal stem cells.

BACKGROUND: Osteoporosis is a metabolic bone disorder that leads to low bone mass and microstructural deterioration of bone tissue and increases bone fractures. Resveratrol, a natural polyphenol compound, has pleiotropic effects including anti-oxidative, anti-aging, and anti-cancer effects. Resveratrol also has roles in increasing osteogenesis and in upregulating mitochondrial biogenesis of bone marrow-derived mesenchymal stem cells (BM-MSCs). However, it is still unclear that resveratrol can enhance osteogenic differentiation or mitochondrial biogenesis of periosteum-derived MSCs (PO-MSCs), which play key roles in bone tissue maintenance and fracture healing. Thus, in order to test a possible preventive or therapeutic effect of resveratrol on osteoporosis, this study investigated the effects of resveratrol treatments on osteogenic differentiation and mitochondrial biogenesis of PO-MSCs. METHODS: The optimal doses of resveratrol treatment on PO-MSCs were determined by cell proliferation and viability assays. Osteogenic differentiation of PO-MSCs under resveratrol treatment was assessed by alkaline phosphatase activities (ALP, an early biomarker of osteogenesis) as well as by extracellular calcium deposit levels (a late biomarker). Mitochondrial biogenesis during osteogenic differentiation of PO-MSCs was measured by quantifying both mitochondrial mass and mitochondrial DNA (mtDNA) contents. RESULTS: Resveratrol treatments above 10 µM seem to have negative effects on cell proliferation and viability of PO-MSCs. Resveratrol treatment (at 5 µM) on PO-MSCs during osteogenic differentiation increased both ALP activities and calcium deposits compared to untreated control groups, demonstrating an enhancing effect of resveratrol on osteogenesis. In addition, resveratrol treatment (at 5 µM) during osteogenic differentiation of PO-MSCs increased both mitochondrial mass and mtDNA copy numbers, indicating that resveratrol can bolster mitochondrial biogenesis in the process of PO-MSC osteogenic differentiation. CONCLUSION: Taken together, the findings of this study describe the roles of resveratrol in promoting osteogenesis and mitochondrial biogenesis of human PO-MSCs suggesting a possible application of resveratrol as a supplement for osteoporosis and/or osteoporotic fractures.

Mapping human serum-induced gene networks as a basis for the creation of biomimetic periosteum for bone repair.

BACKGROUND: The periosteum is a highly vascularized, collagen-rich tissue that plays a crucial role in directing bone repair. This is orchestrated primarily by its resident progenitor cell population. Indeed, preservation of periosteum integrity is critical for bone healing. Cells extracted from the periosteum retain their osteochondrogenic properties and as such are a promising basis for tissue engineering strategies for the repair of bone defects. However, the culture expansion conditions and the way in which the cells are reintroduced to the defect site are critical aspects of successful translation. Indeed, expansion in human serum and implantation on biomimetic materials has previously been shown to improve in vivo bone formation. AIM: This study aimed to develop a protocol to allow for the expansion of human periosteum derived cells (hPDCs) in a biomimetic periosteal-like environment. METHODS: The expansion conditions were defined through the investigation of the bioactive cues involved in augmenting hPDC proliferative and multipotency characteristics, based on transcriptomic analysis of cells cultured in human serum. RESULTS: Master regulators of transcriptional networks were identified, and an optimized periosteum-derived growth factor cocktail (PD-GFC; containing ß-estradiol, FGF2, TNFα, TGFß, IGF-1 and PDGF-BB) was generated. Expansion of hPDCs in PD-GFC resulted in serum mimicry with regard to the cell morphology, proliferative capacity and chondrogenic differentiation. When incorporated into a three-dimensional collagen type 1 matrix and cultured in PD-GFC, the hPDCs migrated to the surface that represented the matrix topography of the periosteum cambium layer. Furthermore, gene expression analysis revealed a down-regulated WNT and TGFß signature and an up-regulation of CREB, which may indicate the hPDCs are recreating their progenitor cell signature. CONCLUSION: This study highlights the first stage in the development of a biomimetic periosteum, which may have applications in bone repair.

Biomimetic organic-inorganic hybrid hydrogel electrospinning periosteum for accelerating bone regeneration.

Periosteum as an important component in the construct of bone is mainly responsible for providing nourishment and regulating osteogenic differentiation. When bone defect happens, the functionality of periosteum will also be influenced, furthermore, it will finally hamper the process of bone regeneration. However, fabrication of an artificial periosteum with the capabilities in accelerating angiogenesis and osteogenesis in the defect area is still a challenge for researchers. In this study, we fabricated an organic-inorganic hybrid biomimetic periosteum by electrospinning, which can induce mineralization in situ and control the ions release for long-term in local area. Further, this system exhibited potential capabilities in promoting in vitro, which means the potentiality in accelerating bone regeneration in vivo. Calcium phosphate nanoparticles (CaPs) were fabricated by emulsion method, then CaPs were further incorporated with gelatin-methacryloyl (GelMA) by electrospinning fibers to construct the hybrid hydrogel fibers. The fibers exhibited satisfactory morphology and mechanical properties, additionally, controlled ions release could be observed for over 10 days. Further, significant mineralization was proved on the surface of hybrid fibers after 7 days and 14 days' co-incubation with simulated body fluid (SBF). Then, favorable biocompatibility of the hybrid fibers was approved by co-cultured with MC3T3-E1 cells. Finally, the hybrid fibers exhibited potential capabilities in promoting angiogenesis and osteogenesis by co-culture with HUVECs and MC3T3-E1 cells. This biomimetic organic-inorganic hybrid hydrogel electrospinning periosteum provided a promising strategy to develop periosteum biomaterials with angiogenesis and osteogenesis capabilities.

A new improvement: subperiosteal cocktail application to effectively reduce pain and blood loss after total knee arthroplasty.

BACKGROUND: Pain and blood loss after total knee arthroplasty (TKA) are unsolved clinical problems. Some studies reported that periarticular cocktail injection can effectively reduce pain and blood loss. However, there was no gold standard about the cocktail ingredient and injection location. More osteotomy and less soft tissue release in TKA with mild deformity; besides, plenty of nerves and blood vessels are contained in the periosteums and bone marrow. In this study, we aimed to detect the clinical results of subperiosteal cocktail application in TKA. METHODS: Two groups were included according to the different injection location in our study. In group 1, cocktails were injected into the muscles, tendons, suprapatellar bursa, and subpatellar bursa surrounding knee joint. In group 2, cocktail injection was performed under the periosteum of the distal femur and proximal tibia. Our primary outcomes were visual analogue scale (VAS) and hemoglobin (Hb), and the secondary outcomes were wound healing, infection, deep vein thrombosis (DVT), operation time, and hospitalization. RESULTS: At the first operative day, the mean (standard deviation) VAS score in a state of static was lower in group 2 compared with group 1 (0.98 ± 0.27 in group 1 and 0.86 ± 0.60 in group 2, p < 0.05). In the state of flexion and extension, the mean (standard deviation) VAS was 1.61 ± 0.66 in group 1 and 1.10 ± 0.57 in group 2 (p < 0.05). The mean (standard deviation) blood loss was higher in group 1 than in group 2 at the first postoperative day (440.19 (167.68) ml in group 1 and 333.67 (205.99) ml in group 2, p < 0.05). At the third day after surgery, the mean (standard deviation) blood loss was 686.44 (140.29) ml in group 1 and 609.19 (260.30) ml in group 2, and there was significant difference between these two groups (p < 0.05). CONCLUSIONS: We concluded that subperiosteal cocktail injection can significantly reduce pain and blood loss compared with periarticular cocktail injection after TKA.

Programmed Sustained Release of Recombinant Human Bone Morphogenetic Protein-2 and Inorganic Ion Composite Hydrogel as Artificial Periosteum.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) and bioceramic are the widely used bioactive factors in treatment of bone defects, but these easily cause side effects because of uncontrollable local concentration. In this study, rhBMP-2 was grafted on the surface of mesoporous bioglass nanoparticles (MBGNs) with an amide bond and then photo-cross-linked together with methacrylate gelatin (GelMA); in this way, a GelMA/MBGNs-rhBMP-2 hydrogel membrane was fabricated to release rhBMP-2 in a controllable program during the early bone regeneration period and then release calcium and silicon ions to keep promoting osteogenesis instead of rhBMP-2 in a long term. In this way, rhBMP-2 can keep releasing for 4 weeks and then the ions keep releasing after 4 weeks; this process is matched to early and late osteogenesis procedures. In vitro study demonstrated that the early release of rhBMP-2 can effectively promote local cell osteogenic differentiation in a short period, and then, the inorganic ions can promote cell adhesion not only in the early stage but also keep promoting osteogenic differentiation for a long period. Finally, the GelMA/MBGNs-rhBMP-2 hydrogel shows a superior capacity in long-term osteogenesis and promoting bone tissue regeneration in rat calvarial critical size defect. This GelMA/MBGNs-rhBMP-2 hydrogel demonstrated a promising strategy for the controllable and safer use of bioactive factors such as rhBMP-2 in artificial periosteum to accelerate bone repairing.

Periosteal Reaction Possibly Induced by Pazopanib: A Case Report and Literature Review.

BACKGROUND: Although complications associated with pazopanib, a multitarget tyrosine kinase inhibitor, are known, periosteal reaction as a side effect has never been reported. OBSERVATION: We present a case involving a male pediatric patient with desmoid tumors treated for 6 months with pazopanib who presented with pain and periosteal reaction in the ilium and scapula. Three months after termination of pazopanib therapy, the periosteal reaction in the scapula resolved and that in the ilium improved. CONCLUSION: Children receiving pazopanib presenting with focal pain should be examined for the periosteal reaction; this knowledge may facilitate correct diagnosis of symptoms as a drug-associated finding.

Phosphorylation of chitosan to improve osteoinduction of chitosan/xanthan-based scaffolds for periosteal tissue engineering.

The periosteum is a membrane that surrounds bones, providing essential cellular and biological components for fracture healing and bone repair. Tissue engineered scaffolds able to function as periosteum substitutes can significantly improve bone regeneration in severely injured tissues. Efforts to develop more bioactive and tunable periosteal substitutes are required to improve the success of this tissue engineering approach. In this work, a chemical modification was performed in chitosan, a polysaccharide with osteoconductive properties, by introducing phosphate groups to its structure. The phosphorylated polymer (Chp) was used to produce chitosan-xanthan-based scaffolds for periosteal tissue engineering. Porous and mechanically reinforced matrices were obtained with addition of the surfactant Kolliphor® P188 and the silicone rubber Silpuran® 2130A/B. Scaffolds properties, such as large pore sizes (850-1097 µm), micro-roughness and thickness (0.7-3.5 mm in culture medium), as well as low thrombogenicity compared to standard implantable materials, extended degradation time and negligible cytotoxicity, enable their application as periosteum substitutes. Moreover, the higher adsorption of bone morphogenetic protein mimic (cytochrome C) by Chp-based formulations suggests improved osteoinductivity of these materials, indicating that, when used in vivo, the material would be able to concentrate native BMPs and induce osteogenesis. The scaffolds produced were not toxic to adipose tissue-derived stem cells, however, cell adhesion and proliferation on the scaffolds surfaces can be still further improved. The mineralization observed on the surface of all formulations indicates that the materials studied have promising characteristics for the application in bone regeneration.

Concentrated growth factor promotes proliferation, osteogenic differentiation, and angiogenic potential of rabbit periosteum-derived cells in vitro.

OBJECTIVE: The aim of this research is to investigate the effects of concentrated growth factor (CGF) on the proliferation, osteogenic differentiation, and angiogenic potential of rabbit periosteum-derived cells (PDCs) in vitro. METHODS: PDCs were isolated from the femoral and tibial periosteum of rabbits and cultured with or without CGF membranes or CGF conditioned media. Scanning electron microscopy (SEM) was used for the structural characterization. Cell Counting Kit-8 assay was used to measure cell proliferation. Alkaline phosphatase (ALP) activity of PDCs was also measured. Immunohistochemistry was used to detect the expression of CD34. Enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qPCR), and Western blot were used to evaluate the secretion and expression levels of osteogenic differentiation markers (bone morphogenetic protein-2, type I collagen, osteocalcin) and angiogenesis markers (vascular endothelial growth factor, basic fibroblast growth factor) in supernatants and PDCs at days 3, 7, 14, and 21. RESULTS: The SEM analysis showed a dense three-dimensional fibrin network in CGF, and CGF membranes were covered by PDCs with elongated or polygonal morphological features. Compared with the control group, CGF significantly promoted the proliferation of PDCs during the experimental period (p < 0.05). Immunohistochemistry revealed that PDCs were dispersedly distributed among the CGF substrates, and CD34-positive cells were also present. Moreover, CGF significantly increased the ALP activity and upregulated the expression and secretion of osteogenic differentiation and angiogenesis markers in PDCs at days 3, 7, 14, and 21 (p < 0.05). CONCLUSION: CGF can increase the proliferation and promote the osteogenic differentiation and angiogenic potential of PDCs in vitro. These results indicate that CGF can be used as a new therapeutic means for biotechnological and clinical applications.

Microcirculatory consequences of limb ischemia/reperfusion in ovariectomized rats treated with zoledronic acid.

BACKGROUND: Nitrogen-containing bisphosphonates (BIS) are potent therapeutics in osteoporosis, but their use may result in osteonecrotic side-effects in the maxillofacial region. Periosteal microcirculatory reactions may contribute to the development of bone-healing complications, particularly in osteoporotic bones, where ischemia-reperfusion (IR) events often develop during orthopaedic/trauma interventions. The effect of BIS on the inflammatory reactions of appendicular long bones has not yet been evaluated; thus, we aimed to examine the influence of chronic zoledronate (ZOL) administration on the periosteal microcirculatory consequences of hindlimb IR in osteopenic rats. MATERIALS AND METHODS: Twelve-week-old female Sprague-Dawley rats were ovariectomized (OVX) or sham-operated, and ZOL (80 µg/kg iv, weekly) or a vehicle was administered for 8 weeks, 4 weeks after the operation. At the end of the pre-treatment protocols, 60-min limb ischemia was induced, followed by 180-min reperfusion. Leukocyte-endothelial interactions were quantitated in tibial periosteal postcapillary venules by intravital fluorescence videomicroscopy. CD11b expression of circulating polymorphonuclear leukocytes (PMN, flow cytometry) and plasma TNF-alpha levels (ELISA) were also determined. Two-way RM ANOVA followed by the Holm-Sidak and Dunn tests was used to assess differences within and between groups, respectively. RESULTS: Limb IR induced significant increases in PMN rolling and firm adhesion in sham-operated and OVX rats, which were exacerbated temporarily in the first 60 min of reperfusion by a ZOL treatment regimen. Postischemic TNF-alpha values showed a similar level of postischemic elevations in all groups, whereas CD11b expression only increased in rats not treated with ZOL. CONCLUSIONS: The present data do not show substantial postischemic periosteal microcirculatory complications after chronic ZOL treatment either in sham-operated or OVX rats. The unaltered extent of limb IR-induced local periosteal microcirculatory reactions in the presence of reduced CD11b adhesion molecule expression on circulating PMNs, however, may be attributable to local endothelial injury/activation caused by ZOL.

Platelet-Rich Fibrin Extract: A Promising Fetal Bovine Serum Alternative in Explant Cultures of Human Periosteal Sheets for Regenerative Therapy.

In 2004, we developed autologous periosteal sheets for the treatment of periodontal bone defects. This regenerative therapy has successfully regenerated periodontal bone and augmented alveolar ridge for implant placement. However, the necessity for 6-week culture is a limitation. Here, we examined the applicability of a human platelet-rich fibrin extract (PRFext) as an alternative to fetal bovine serum (FBS) for the explant culture of periosteal sheets in a novel culture medium (MSC-PCM) originally developed for maintaining mesenchymal stem cells. Small periosteum tissue segments were expanded in MSC-PCM + 2% PRFext for 4 weeks, and the resulting periosteal sheets were compared with those prepared by the conventional method using Medium199 + 10% FBS for their growth rate, cell multilayer formation, alkaline phosphatase (ALP) activity, and surface antigen expression (CD73, CD90, and CD105). Periosteal sheets grew faster in the novel culture medium than in the conventional medium. However, assessment of cell shape and ALP activity revealed that the periosteal cells growing in the novel medium were relatively immature. These findings suggest that the novel culture medium featuring PRFext offers advantages by shortening the culture period and excluding possible risks associated with xeno-factors without negatively altering the activity of periosteal sheets.

Exercise-induced sympathetic dilatation in arterioles of the guinea pig tibial periosteum.

Strength training induces not only muscle growth but also increased bone strength, a change that is expected to be associated with increased bone blood flow. However, the effects of exercise on contractile properties of bone microvascultaure have not been investigated. Once-a-week strength training with electrical muscle stimulation was applied unilaterally to tibialis anterior muscle of guinea pigs, while muscle force was measured from both legs to compare their muscle strength and endurance. After 10 weeks of training, changes in the arteriolar diameters of isolated periosteum taken from both trained and non-trained legs were measured using a video tracking system. Electrical field stimulation evoked a phasic constriction followed by a sustained dilatation in periosteal arterioles of trained legs, while triggering only vasoconstriction in the arterioles of non-trained legs. In trained leg arterioles, phentolamine, an α-adrenoceptor antagonist, inhibited both the constriction and dilatation. Prazosin, an α1-adrenoceptor antagonist, inhibited only the constriction, while yohimbine, α2-adrenoceptor antagonist, or l-nitro arginine (L-NA), a nitric oxide (NO) synthase inhibitor, inhibited the dilatation. In non-trained leg arterioles, phentolamine or prazosin largely suppressed the constriction, but failed to unmask any dilatation. Consistently, noradrenaline (NAd)-induced arteriolar constriction was enhanced and prolonged by L-NA in trained but not non-trained side arterioles. Thus, NAd released from sympathetic nerves appears to activate endothelial α2-adrenoceptors to release NO resulting in the sustained dilatation of periosteum arterioles from trained leg. The altered sympathetic vasomotor function would facilitate the blood supply to the bone and may contribute to the exercise-induced bone strength gain.

Temporary inhibition of the plasminogen activator inhibits periosteal chondrogenesis and promotes periosteal osteogenesis during appendicular bone fracture healing.

INTRODUCTION: Aminocaproic acid is approved as an anti-fibrinolytic for use in joint replacement and spinal fusion surgeries to limit perioperative blood loss. Previous animal studies have demonstrated a pro-osteogenic effect of aminocaproic acid in spine fusion models. Here, we tested if aminocaproic acid enhances appendicular bone healing and we sought to uncover the effect of aminocaproic acid on osteoprogenitor cells (OPCs) during bone regeneration. METHODS: We employed a well-established murine femur fracture model in adult C57BL/6J mice after receiving two peri-operative injections of aminocaproic acid. Routine histological assays, biomechanical testing and micro-CT analyses were utilized to assess callus volume, and strength, progenitor cell proliferation, differentiation, and remodeling in vivo. Two disparate ectopic transplantation models were used to study the effect of the growth factor milieu within the early fracture hematoma on osteoprogenitor cell fate decisions. RESULTS: Aminocaproic acid treated femur fractures healed with a significantly smaller cartilaginous callus, and this effect was also observed in the ectopic transplantation assays. We hypothesized that aminocaproic acid treatment resulted in a stabilization of the early fracture hematoma, leading to a change in the growth factor milieu created by the early hematoma. Gene and protein expression analysis confirmed that aminocaproic acid treatment resulted in an increase in Wnt and BMP signaling and a decrease in TGF-ß-signaling, resulting in a shift from chondrogenic to osteogenic differentiation in this model of endochondral bone formation. CONCLUSION: These experiments demonstrate for the first time that inhibition of the plasminogen activator during fracture healing using aminocaproic acid leads to a change in cell fate decision of periosteal osteoprogenitor cells, with a predominance of osteogenic differentiation, resulting in a larger and stronger bony callus. These findings may offer a promising new use of aminocaproic acid, which is already FDA-approved and offers a very safe risk profile.