Thymosin β4 administration enhances fracture healing in mice

Thymosin β₄ (Tβ₄) is a regenerative peptide that we hypothesized would promote healing of fractured bone. Mice received a bilateral fibular osteotomy and were given i.p. injections of either Tβ₄ (6 mg/kg) or saline. Calluses from saline‐ and Tβ₄‐treated mice were analyzed for: (1) biomechanical properties and (2) composition using micro‐computed tomography (µCT) and histomorphometry. Biomechanical analysis showed that Tβ₄‐treated calluses had a 41% increase in peak force to failure (p < 0.01) and were approximately 25% stiffer (p < 0.05) than saline‐treated controls. µCT analysis at 21 days post‐fracture showed that the fractional volume of new mineralized tissue and new highly mineralized tissue were respectively 18% and 26% greater in calluses from Tβ₄‐treated mice compared to controls (p < 0.01; p < 0.05, respectively). Histomorphometry complemented the µCT data; at 21 days post‐fracture, Tβ₄‐treated calluses were almost 23% smaller (p < 0.05), had nearly 47% less old cortical bone (p < 0.05) and had a 31% increase in new trabecular bone area/total callus area fraction compared with controls (p < 0.05). Our finding of enhanced biomechanical properties of fractures in mice treated with Tβ₄ provides novel evidence of the therapeutic potential of this peptide for treating bone fractures. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1277–1282, 2014.     

Curcumin accelerates cutaneous wound healing via multiple biological actions: The involvement of TNF‐α, MMP‐9, α‐SMA,and collagen

Curcumin, a constituent of the turmeric plant, has antitumor, anti‐inflammatory, and antioxidative effects, but its effects on wound healing are unclear. We created back wounds in 72 mice and treated them with or without topical curcumin (0.2 mg/mL) in Pluronic F127 gel (20%) daily for 3, 5, 7, 9, and 12 days. Healing in wounds was evaluated from gross appearance, microscopically by haematoxylin and eosin staining, by immunohistochemistry for tumour necrosis factor alpha and alpha smooth muscle actin, and by polymerase chain reaction amplification of mRNA expression levels. Treatment caused fast wound closure with well‐formed granulation tissue dominated by collagen deposition and regenerating epithelium. Curcumin increased the levels of tumour necrosis factor alpha mRNA and protein in the early phase of healing, which then decreased significantly. However, these levels remained high in controls. Levels of collagen were significantly higher in curcumin‐treated wounds. Immunohistochemical staining for alpha smooth muscle actin was increased in curcumin‐treated mice on days 7 and 12. Curcumin treatment significantly suppressed matrix metallopeptidase‐9 and stimulated alpha smooth muscle levels in tumour necrosis factor alpha‐treated fibroblasts via nuclear factor kappa B signalling. Thus, topical curcumin accelerated wound healing in mice by regulating the levels of various cytokines.     

Local release of pioglitazone (a peroxisome proliferator‐activated receptor γ agonist) accelerates proliferation and remodeling phases of wound healing

Peroxisome proliferator‐activated receptor γ (PPARγ) is a member of the nuclear receptor superfamily known for its anti‐inflammatory and macrophage differentiation effects, as well as its ability to promote fat cell differentiation and reduce insulin resistance. Pioglitazone (Pio) is a PPARγ agonist used clinically as an anti‐diabetic agent for improving insulin sensitivity in patients with diabetes. The objective of this study was to develop a drug delivery system (DDS) for the local release of Pio to promote wound healing. Pio of low aqueous solubility was water‐solubilized by micelles formed from gelatin grafted with L‐lactic acid oligomers, and incorporated into a biodegradable gelatin hydrogel. An 8‐mm punch biopsy tool was used to prepare two skin wounds on either side of the midline of 8‐week‐old mice. Wounds were treated by the hydrogels with (Pio‐hydrogel group) or without (control group) Pio, and the wound area were observed 1, 4, 7, and 14 days after treatment. In addition, a protein assay and immunohistological stain were performed to determine the effects of the Pio‐hydrogel on inflammation and macrophage differentiation. The Pio‐hydrogels promote wound healing. Moreover, Western blotting analysis demonstrated that treatment with Pio‐hydrogels resulted in decreased levels of the cytokines MIP‐2 and TGF‐β, and increased levels of glucose‐regulating adiponectin. It is concluded that Pio‐incorporated hydrogels promote the proliferation and remodeling phases of wound healing, and may prove to be effective as wound dressings.     

Combined effects of TNF‐α, IL‐1β, and HIF‐1α on MMP‐2 production in ACL fibroblasts under mechanical stretch: An in vitro study

The dynamics between inflammatory factors, mechanical stress, and healing factors, in an intra‐articular joint, are very complex after injury. Injury to intra‐articular tissue [anterior cruciate ligament (ACL), synovium] results in hypoxia, accumulation of various pro‐inflammatory factors, cytokines, and metalloproteases. Although the presence of increased amounts of matrix‐metalloproteinases (MMP) in the joint fluid after knee injury is considered the key factor for ACL poor healing ability; however, the exact role of collective participants of the joint fluid on MMP‐2 activity and production has not been fully studied yet. To investigate the combined effects of mechanical injury, inflammation and hypoxia induced factor‐1α (HIF‐1α) on induction of MMP‐2; we mimicked the microenvironment of joint cavity after ACL injury. The results show that TNF‐α and IL‐1β elevate the activity of MMP‐2 in a dose‐ and time‐dependent manner. In addition, mechanical stretch further enhances the MMP‐2 protein levels with TNF‐α, IL‐1β, and their mixture. CoCl₂‐induced HIF‐1α (100 and 500 µM) also increases the levels and activity of MMP‐2. Mechanical stretch has a strong additional effect on MMP‐2 production with HIF‐1α. Our results conclude that mechanical injury, HIF‐1α and inflammatory factors collectively induce increased MMP‐2 production in ACL fibroblasts, which was inhibited by NF‐κB pathway inhibitor (Bay‐11‐7082). © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1008–1014, 2011     

Interleukin‐1β stimulates stromal‐derived factor‐1α expression in human subacromial bursa

Chemokines produced by synoviocytes of the subacromial bursa are up‐regulated in subacromial bursitis and rotator cuff disease. We hypothesized that SDF‐1α production in bursal synoviocytes may be induced by local cytokines such as interleukin IL‐1β and IL‐6. Subacromial bursa specimens were obtained from patients undergoing shoulder surgery. Bursal specimens were stained with anti‐human antibodies to IL‐1, IL‐6, and SDF‐1α by immunohistochemistry and compared to normal and rheumatoid controls. Bursal cells were also isolated from specimens and cultured. Early passaged cells were then treated with cytokines (IL‐1β and IL‐6) and SDF‐1α expression was measured by ELISA and RT‐PCR. SDF‐1α, IL‐1β, and IL‐6 were expressed at high levels in bursitis specimens from human subacromial bursa compared to normal controls. In cultured bursal synoviocytes, there was a dose‐dependent increase in SDF‐1α production in the supernatants of cells treated with IL‐1β. SDF‐1α mRNA expression was also increased in bursal cells treated with IL‐1β. IL‐6 caused a minimal but not statistically significant increase in SDF‐1α expression. SDF‐1α, IL‐1β, and IL‐6 are expressed in the inflamed human subacromial bursal tissues in patients with subacromial bursitis. In cultured bursal synoviocytes, SDF‐1α gene expression and protein production are stimulated by IL‐1β. IL‐1β produced by bursal syvoviocytes and inflammatory cells in the human subacromial bursa is an important signal in the inflammatory response that occurs in subacromial bursitis and rotator cuff disease. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1695–1699, 2011     

Oestradiol‐17β is a local factor inducing the early stage of spermatogenesis in mouse testes

This study was undertaken to elucidate the effect of testicular oestradiol‐17β (E₂) on spermatogenesis. Spermatogonial development and spermatogenic gene expression in testicular germ cells were investigated using an in vitro culture system supplemented with E₂. E₂ stimulated spermatocytogenic development of cultured testicular germ cells regardless of the addition of follicle‐stimulating hormone and testosterone to the culture medium. E₂ also induced the expression of genes encoding synaptonemal complex protein 1 and protamine 1, proteins required for spermatogenesis. In conclusion, the results of this study suggest that E₂ is a spermatocytogenic factor that acts via the stimulation of spermatogenic gene expression.     

Indirubin‐3′‐Oxime Reverses Bone Loss in Ovariectomized and Hindlimb‐Unloaded Mice Via Activation of the Wnt/β‐Catenin Signaling

Osteoporosis is a major global health issue in elderly people. Because Wnt/β‐catenin signaling plays a key role in bone homeostasis, we screened activators of this pathway through cell‐based screening, and investigated indirubin‐3′‐oxime (I3O), one of the positive compounds known to inhibit GSK3β, as a potential anti‐osteoporotic agent. Here, we show that I3O activated Wnt/β‐catenin signaling via inhibition of the interaction of GSK3β with β‐catenin, and induced osteoblast differentiation in vitro and increased calvarial bone thickness ex vivo. Intraperitoneal injection of I3O increased bone mass and improved microarchitecture in normal mice and reversed bone loss in an ovariectomized mouse model of age‐related osteoporosis. I3O also increased thickness and area of cortical bone, indicating improved bone strength. Enhanced bone mass and strength correlated with activated Wnt/β‐catenin signaling, as shown by histological analyses of both trabecular and cortical bones. I3O also restored mass and density of bone in hindlimb‐unloaded mice compared with control, suspended mice, demonstrating bone‐restoration effects of I3O in non‐aged–related osteoporosis as well. Overall, I3O, a pharmacologically active small molecule, could be a potential therapeutic agent for the treatment and prevention of osteoporosis. © 2014 American Society for Bone and Mineral Research.     

Induction of benign prostatic hyperplasia in intact dogs by near-physiological levels of 5α-dihydrotestosterone and 17β-estradiol

Benign prostatic hyperplasia was induced in mongrel dogs treated for 60 days with one silastic implant containing 17β-estradiol and four containing 5α-dihydrotestosterone. The condition was characterized by (1) a marked increase of the stromal elements, particularly the stromal septa between the individual glands, (2) a slight increase in prostatic volume, and (3) a morphology that resembled spontaneous complex benign prostatic hyperplasia in the dog. Other groups of animals that remained untreated or received only 17β-estradiol or only 5α-dihydrotestosterone did not develop this condition. Prostate volumes decreased by 14% in the estrogen-treated dogs, whereas they increased in the androgen-treated animals by 6% compared to pretreatment prostate volumes. The morphology of the epithelium of the prostates of androgen-treated animals was not different from that of controls despite the increase in prostate volume. The serum 17β-estradiol and 5α-dihydrotestosterone concentrations were increased from 25 ± 2 (mean ± SEM) and 256 ± 42 pg/mL, respectively, in control dogs to 52 ± 37 and 562 ± 37 pg/mL, respectively, in the dogs treated with the hormone combination. Thus, hormone concentrations were two- to three-fold higher than control values, and the ratio of estradiol-17β to 5α-dihydrotestosterone was increased by up to 19%. These data demonstrate that treatment of dogs with low levels of estrogen and androgen may be an excellent model for the study of spontaneous complex benign prostatic hyperplasia in aging men.     

Potential pathological role of pro‐inflammatory cytokines (IL‐6, TNF‐α, and IL‐17) in xenotransplantation

The major limitation of organ transplantation is the shortage of available organs from deceased human donors which leads to the deaths of thousands of patients each year. Xenotransplantation is considered to be an effective way to resolve the problem. Immune rejection and coagulation dysfunction are two major hurdles for the successful survival of pig xenografts in primate recipients. Pro‐inflammatory cytokines, such as IL‐6, TNF‐α, and IL‐17, play important roles in many diseases and in allotransplantation. However, the pathological roles of these pro‐inflammatory cytokines in xenotransplantation remain unclear. Here, we briefly review the signaling transduction and expression regulation of IL‐6, TNF‐α, and IL‐17 and evaluate their potential pathological roles in in vitro and in vivo models of xenotransplantation. We found that IL‐6, TNF‐α, and IL‐17 were induced in most in vitro or in vivo xenotransplantation model. Blockade of these cytokines using gene modification, antibody, or inhibitor had different effects in xenotransplantation. Inhibition of IL‐6 signaling with tocilizumab decreased CRP but did not increase xenograft survival. The one possible reason is that tocilizumab can not suppress IL‐6 signaling in porcine cells or organs. Other drugs which inhibit IL‐6 signaling need to be investigated in xenotransplantation model. Inhibition of TNF‐α was beneficial for the survival of xenografts in pig‐to‐mouse, rat, or NHP models. Blockade of IL‐17 using a neutralizing antibody also increased xenograft survival in several animal models. However, the role of IL‐17 in the pig‐to‐NHP xenotransplantation model remains unclear and needs to be further investigated. Moreover, blockade of TNF‐α and IL‐6 together has got a better effect in pig‐to‐baboon kidney xenotransplantation. Blockade two or even more cytokines together might get better effect in suppressing xenograft rejection. Better understanding the role of these cytokines in xenotransplantation will be beneficial for choosing better immunosuppressive strategy or producing genetic modification pig.     

β‐catenin promotes bone formation and suppresses bone resorption in postnatal growing mice

Genetic studies in the mouse have demonstrated multiple roles for β‐catenin in the skeleton. In the embryo, β‐catenin is critical for the early stages of osteoblast differentiation. Postnatally, β‐catenin in mature osteoblasts and osteocytes indirectly suppresses osteoclast differentiation. However, a direct role for β‐catenin in regulating osteoblast number and/or function specifically in the postnatal life has not been demonstrated. Addressing this knowledge gap is important because low‐density lipoprotein receptor‐related protein 5 (LRP5), a coreceptor for WNT signaling proposed to function through β‐catenin, controls osteoblast number and function in postnatal mice or humans. To overcome the neonatal lethality caused by embryonic deletion of β‐catenin in early‐stage osteoblast‐lineage cells, we use the Osx‐CreER^T2 mouse strain to remove β‐catenin in Osterix (Osx)‐expressing cells by administering tamoxifen (TM) temporarily to postnatal mice. Lineage‐tracing experiments in the long bones demonstrate that Osx‐CreER^T2 targets predominantly osteoblast‐lineage cells on the bone surface, but also transient progenitors that contribute to bone marrow stromal cells and adipocytes. Deletion of β‐catenin by this strategy greatly reduces the bone formation activity of the targeted osteoblasts. However, the targeted osteoblasts rapidly turn over and are replaced by an excessive number of non‐targeted osteoblasts, causing an unexpected increase in bone formation, but an even greater increase in osteoclast number and activity produces a net effect of severe osteopenia. With time, the mutant mice also exhibit a marked increase in bone marrow adiposity. Thus, β‐catenin in postnatal Osx‐lineage cells critically regulates bone homeostasis by promoting osteoblast activity and suppressing osteoblast turnover, while restraining osteoclast and marrow fat formation. © 2013 American Society for Bone and Mineral Research.     

Overexpression of Human Hydroxysteroid (17β) Dehydrogenase 2 Induces Disturbance in Skeletal Development in Young Male Mice

To understand the function of human hydroxysteroid (17β) dehydrogenase 2 (HSD17B2) in the peripheral tissues in vivo, we studied the bone development in transgenic male mice ubiquitously expressing human HSD17B2. Bones of HSD17B2TG and WT males (26 days and 2 and 6 mo old) were analyzed by pQCT and histomorphometry, and data were correlated with serum testosterone (T), IGF‐I, and osteocalcin concentrations. At the age of 26 days, the body weight of HSD17B2TG males was significantly lower, and the lengths of the tibia and femur of the HSD17B2TG males were significantly shorter. Histomorphometric and pQCT analyses showed lower trabecular and cortical BMD, a markedly smaller area of cortical bone at both of the diaphyses, and a smaller percentage of trabecular bone volume and thickness in the HSD17B2TG males. The data suggested slower osteoblast differentiation and a slower bone formation rate of femoral diaphysis on the periosteum but faster on the endocortical surface in HSD17B2TG males. The altered bone parameters were correlated with low serum T, IGF‐I, and osteocalcin concentrations at the prepubertal age. Interestingly, after puberty, the bone parameters analyzed in the adult HSD17B2TG males were mostly normal, consistent with the normal body weight and normalized serum concentrations of IGF‐I and T. In conclusion, HSD17B2TG males presented with growth retardation and a decreased bone formation rate at prepubertal age. These changes were associated with lower serum IGF‐I, osteocalcin, and T concentrations. It is concluded that the enforced constitutive expression of HSD17B2 disturbs the coordinated action of IGF‐I and sex steroids essential for pubertal bone growth.