Epithelial defect repair in the auricle and auditory meatus by grafting with cultured adipose-derived mesenchymal stem cell aggregate-extracellular matrix.

BACKGROUND: Several patients experience persistent otorrhea after a flawless surgical procedure because of insufficient epithelial healing. Several efforts, such as autologous tissue allograft and xenograft, have been made to halt otorrhea. However, a stable technology to induce temporal epithelial repair is yet to be established. Therefore, this study aims to investigate whether implantation of seeding adipose-derived mesenchymal stem cell (ADMSC) aggregates on extracellular matrix (ECM; herein, ADMSC aggregate-ECM) into damaged skin wound promotes skin regeneration. METHODS: ADMSC aggregate-ECM was prepared using a previously described procedure that isolated ADMSCs from rabbits and applied to the auricle and auditory meatus wound beds of New Zealand white rabbits. Wound healing was assessed by general observation and hematoxylin and eosin (H&E) staining. Secretion of growth factor of the tissue was evaluated by western blotting. Two other groups, namely, ECM and control, were used. Comparisons of three groups were conducted by one-way analysis of variance analysis. RESULTS: ADMSCs adhered tightly to the ECM and quickly formed cell sheets. At 2 weeks, general observation and H&E staining indicated that the wound healing rates in the ADMSC aggregate-ECM (69.02 ±â€Š6.36%) and ECM (59.32 ±â€Š4.10%) groups were higher than that in the control group (43.74 ±â€Š12.15%; P = 0.005, P < 0.001, respectively) in ear auricle excisional wounds. At 7 weeks, The scar elevation index was evidently reduced in the ADMSC aggregate-ECM (2.08 ±â€Š0.87) and ECM (2.31 ±â€Š0.33) groups compared with the control group (4.06 ±â€Š0.45; P < 0.001, P < 0.001, respectively). In addition, the scar elevation index of the ADMSC aggregate-ECM group reached the lowest rate 4 weeks in advance. In auditory meatus excisional wounds, the ADMSC aggregate-ECM group had the largest range of normal skin-like structure at 4 weeks. The ADMSC aggregate-ECM and ECM groups secreted increased amounts of growth factors that contributed to skin regeneration at weeks 1 and 2, respectively. CONCLUSIONS: ADMSC aggregate-ECM and ECM are effective repair materials for wound healing, especially ADMSC aggregate-ECM. This approach will provide a meaningful experimental basis for mastoid epithelium repair in subsequent clinical trials.

The prenyl group contributes to activities of phytoestrogen 8-prenynaringenin in enhancing bone formation and inhibiting bone resorption in vitro.

Previous studies have found that 8-prenylflavonoids have a higher osteogenic activity than do flavonoids, which suggested that the 8-prenyl group may play an active role in bone-protective properties. To address this hypothesis, activities of 8-prenylnaringenin (PNG) and naringenin (NG) in osteoblast and osteoclast differentiation and function were compared in vitro. PNG was found to have a stronger ability than NG to improve osteoblast differentiation and osteogenic function in cultured rat calvarial osteoblasts, as demonstrated by levels of alkaline phosphatase activity, osteocalcin, calcium deposition, and the number and area of mineralized bone nodules, as well as mRNA expression of osteogenesis-related genes Bmp-2, OSX, and Runx-2. In addition, although expression of osteoclastogenic inducer receptor activator of nuclear factor kappa-B ligand (RANKL) was not affected, that of osteoclastogenesis inhibitor osteoprotegerin (OPG) and consequently the OPG/RANKL ratio were increased, more potently by PNG than NG. PNG was also found to have a higher potency than NG in inhibiting the osteoclast formation in rabbit bone marrow cells and their resorptive activity, as revealed by lower numbers of osteoclasts formed, lower numbers and areas of bone resorption pits, and lower mRNA expression levels of tartrate-resistant acid phosphatase and cathepsin K. Furthermore, PNG induced apoptosis of mature osteoclasts at a higher degree and at an earlier time than did NG. These results indicate that the 8-prenyl group plays an important role and contributes to the higher bone-protective activity of PNG in comparison with NG.

Functions and action mechanisms of flavonoids genistein and icariin in regulating bone remodeling.

Increasingly natural products particularly flavonoids are being explored for their therapeutic potentials in reducing bone loss and maintaining bone health. This study has reviewed previous studies on the two better known flavonoids, genistein and icariin, their structures, functions, action mechanisms, relative potency, and potential application in regulating bone remodeling and preventing bone loss. Genistein, an isoflavone abundant in soy, has dual functions on bone cells, able to inhibit bone resorption activity of osteoclasts and stimulate osteogenic differentiation and maturation of bone marrow stromal progenitor cells (BMSCs) and osteoblasts. Genistein is an estrogen receptor (ER)-selective binding phytoestrogen, with a greater affinity to ERß. Genistein inhibits tyrosine kinases and inhibits DNA topoisomerases I and II, and may act as an antioxidant. Genistein enhances osteoblastic differentiation and maturation by activation of ER, p38MAPK-Runx2, and NO/cGMP pathways, and it inhibits osteoclast formation and bone resorption through inducing osteoclastogenic inhibitor osteoprotegerin (OPG) and blocking NF-κB signaling. Icariin, a prenylated flavonol glycoside isolated from Epimedium herb, stimulates osteogenic differentiation of BMSCs and inhibits bone resorption activity of osteoclasts. Icariin, whose metabolites include icariside I, icariside II, icaritin, and desmethylicaritin, has no estrogenic activity. However, icariin is more potent than genistein in promoting osteogenic differentiation and maturation of osteoblasts. The existence of a prenyl group on C-8 of icariin molecular structure has been suggested to be the reason why icariin is more potent than genistein in osteogenic activity. Thus, the prenylflavonoids may represent a class of flavonoids with a higher osteogenic activity.

[Effect of osthol on apoptosis and bone resorption of osteoclasts cultured in vitro].

This study is to investigate the effect of osthol on osteoclasts' activity, bone resorption as well as apoptosis in vitro, and explore the mechanism of osthol in preventing osteoporosis. Osteoclasts were separated from long-limb bones of new born rabbits, cultured in 24-well plate with glass slices and bone slices, and treated by 1 x 10(-5) mol x L(-1) osthol. Osteoclasts were identified by observing live cells with phase contrast microscope, HE staining, TRAP staining and toluidine blue staining of bone resorption pits. The numbers of bone resorption pits were counted as well as the surface area of bone resorption on bone slice. Osteoclasts were stained with acridine orange to detect the cell apoptosis. The ratio of apoptotic osteoclasts was observed under fluorescence microscope. The gene expression of RANKL, OPG, TRAP and p-JNK1/2 protein expression were examined using real time PCR and Western blotting, respectively. Comparing with the control group without osthol, the rates of apoptotic osteoclasts increased obviously and the number and area of bone resorption pits decreased evidently with 1 x 10(-5) mol x L(-1) osthol. There is significant difference between control group and experiment group treated by 1 x 10(-5) mol x L(-1) osthol. Therefore, the osthol through RANK+RANKL/TRAF6/Mkk/JNK signal pathway inhibits the osteoclasts activity, enhances osteoclasts apoptotic and inhibits the bone resorption.

[Effect of isopsoralen on the proliferation and differentiate of osteoblasts in vitro].

OBJECTIVE: To investigate the effect of isopsoralen on proliferation, osteogenic differentiation and calcification capacity of rat calvarial osteoblasts (ROB). METHODS: Segregated neonatal SD rat skull,and digestion with enzyme to obtain bone cells and cultured in MEM containing 10% FBS. Exchange the medium after three days, proceeded serial subcultivation when cells covered with 90% culture dish. Proliferation analysis was performed in 96-well plates use MTT method, isopsoralen's final concentration were 1 x 10(-4), 1 x10(-5), 1 x 10(-6), 1 x 10(-7) mmol/L. Differentiation analysis was performed in 24-well plates, the Alkaline phosphatase activity and calcium salt sediment yield and osteocalcin measured at the 4th, 8th, 12th, 16th day. At 12th day, proceeded ALP stain, and at 14th day for alizarin red staining and calcified nodule count. RESULTS: When the Isopsoralen's final concentration was 1 x 10(-5) mmol/L, there was no significant effect on the ROB's proliferation, but it could promote osteogenesis. It also could raise the ALP activity and calcium salt sediment yield and osteocalcin, increase calcified tubercle amount. CONCLUSION: When the isopsoralen final concentration is 1 x 10(-5) mmol/L, it promoted ROB differentiation and maturation. Isopsoralen may be the active ingredients of preventing anti-osteoporosis in Psoralea corylifolia.

Effects of 50 Hz sinusoidal electromagnetic fields of different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts.

Electromagnetic fields (EMFs) have been used clinically to slow down osteoporosis and promote fracture healing for many years. However, the underlying action mechanisms and optimal parameters of the EMF applications are unclear. In this study, we investigated the effects of treatment for different durations with 50 Hz sinusoidal electromagnetic fields (SEMFs) at different intensities on proliferation, differentiation and mineralization potentials of rat osteoblasts. Osteoblasts isolated from neonatal rats were treated with SEMFs (50 Hz at 0.9 mT-4.8 mT, 0.3 mT interval, 30 min/day up to 15 days). Compared to untreated control, SEMFs inhibited osteoblast proliferation (after 3 days' treatment) but increased alkaline phosphatase (ALP) activity (after treatment for 9 days) from 0.9 mT to 1.8 mT, declined from 1.8 mT until 3.0 mT, and then increased again from 3.0 mT to 3.6 mT and decreased once again from 3.6 mT to 4.8 mT. Numbers of colonies stained positive for ALP after 8 days and mineralized nodules stained by Alizarin red after 10 days showed the same bimodal tendency as with the ALP activity, with two peaks at 1.8 mT and 3.6 mT. SEMFs also bimodally increased Runx-2, Col1α2 and Bmp-2 mRNA expression levels in osteoblasts at 12, 24 and 96 h after exposure. The results indicated that while exposure to 50 Hz SEMFs inhibits the osteoblast proliferation, it significantly promotes differentiation and mineralization potentials of osteoblasts in an intensity-dependent manner with peak activity at 1.8 mT and 3.6 mT.

Osthol, a coumarin isolated from common cnidium fruit, enhances the differentiation and maturation of osteoblasts in vitro.

The effect of osthol on osteoblasts was investigated in primary osteoblastic cells isolated from newborn Wistar rats. Osthol was supplemented into cultured medium at 10⁻7, 10⁻6, 10⁻5 and 10⁻4 mol/l, respectively. No stimulating effect was found on cell proliferation, but 10⁻5 mol/l osthol caused a significant increase in alkaline phosphatase (ALP) activity. Osteogenic differentiation markers were examined over a period of time at this concentration, and compared with control cells that were not supplemented with osthol. The results showed that the ALP activity, osteocalcin secretion and calcium deposition level in cells treated with osthol were 1.52, 2.74 and 2.0 times higher, respectively, than in the control cells. Results of ALP histochemical staining and mineralized bone nodule assays both showed that the number and area achieved in osthol-treated cells were 1.53-fold higher than in control cells. The gene expression of the growth and transcription factors basic fibroblast growth factor, insulin-like growth factor I, bone morphogenetic protein 2 (BMP-2), runt-related gene 2 (Runx-2) and osterix, which are associated with bone development, were also investigated. The increase in mRNA expression was 1.94, 1.74, 1.68, 1.83 and 2.31 times, respectively, higher compared to the control. Furthermore, osthol increased the protein expression of p38 mitogen-activated protein kinase (MAPK) and type I collagen. p38MAPK protein and collagen in osthol-treated cells were 1.42 and 1.58 times higher in osthol-treated cells compared to the control. The results of these studies support the conclusion that osthol significantly enhances the osteogenic differentiation of cultured osteoblasts. The results also indicated that osthol could stimulate the osteoblastic differentiation of rat calvarial osteoblast cultures by the BMP-2/p38MAPK/Runx-2/osterix pathway and that osthol may be used as an important compound in the development of new antiosteoporosis drugs.

[The changes of iNOS and NO in the osteogenic differentiation process of rat bone marrow stromal cells promoted by icariside II].

This study is to investigate the effects on the expression of iNOS and production of NO in the osteogenic differentiation process of rat bone marrow stromal cells (rBMSCs) by icariside II. rBMSCs were cultured by adherence screening method. When the culture dishes were covered with 80% cells, the osteogenic induced cultures were adopted. Icariside II was supplemented into the culture at 1 x 10(-5) mol x L(-1). The activity of iNOS, content of NO and osteogenic differentiation markers including alkaline phosphatase (ALP) activity, CFU-FALP and mineralized bone nodules were compared among the icariside II-supplemented group, L-NMAE group, icariside II + L-NAME group and the control. Total RNA was isolated and the gene expression of iNOS, Osterix and Runx-2 was investigated by real-time PCR. Total protein was also isolated and the secretion of iNOS and collagen I was examined by Western blotting. Icariside II can significantly improved ALP activity, CFU-FALP amount and mineralized nodules. Besides, the mRNA level of factors related to the osteogenic differentiation includes Osterix and Runx-2 also enhanced. The secretion of collagen I also promoted significantly. But all of these effects can be inhibited by L-NAME which can specifically inhibit the activity of iNOS. Icariside II enhances the osteogenic differentiation of rBMSCs significantly, but if the activity of iNOS was blocked by L-NAME, the osteogenic differentiation markers decrease accompanied with iNOS and NO decrease, suggesting that icariside II stimulates the osteogenic differentiation via enhancing the activity of iNOS and promoting the generation of NO.

Icariin is more potent than genistein in promoting osteoblast differentiation and mineralization in vitro.

There has been a strong interest in searching for natural therapies for osteoporosis. Genistein, an isoflavone abundant in soy, and icariin, a prenylated flavonol glycoside isolated from Epimedium Herb, have both been identified to exert beneficial effects in preventing postmenopausal bone loss. However, the relative potency in osteogenesis between the individual phytoestrogen flavonoids remains unknown. The present study compared ability of genistein and icariin in enhancing differentiation and mineralization of cultured rat calvarial osteoblasts in vitro. Dose-dependent studies in osteoblast differentiation measuring alkaline phosphatase (ALP) activity revealed optimal concentrations of genistein and icarrin for stimulating osteogenesis to be both at 10(-5) M. Time course studies comparing the two compounds both at 10(-5) M demonstrated that icariin treatment always produced higher ALP activity, more and larger areas of CFU-F(ALP) colonies and mineralized nodules, more osteocalcin secretion, and calcium deposition, and a higher level of mRNA expression of osteogenesis-related genes COL1α2, BMP-2, OSX, and RUNX-2. However, they inhibited the proliferation of osteoblasts to a similar degree. In conclusion, although future in vivo studies are required to investigate whether icariin is more efficient in improving bone mass and/or preventing bone loss, our in vitro studies have demonstrated that icariin has a stronger osteogenic activity than genistein. In addition, while the prenyl group on C-8 of icariin could be the active group that takes part in osteoblastic differentiation and explains its greater potency in osteogenesis, mechanisms of action, and reasons for the relative potency of icariin versus genistein need to be further studied.

[Effect of Osthol on the proliferation and differentiate of osteoblasts in vitro].

OBJECTIVE: To investigate the effects of Osthol on the proliferation and differentiation of osteoblasts of rats (rat calvarial osteoblasts, ROB) cultured in vitro. METHODS: The neonatal SD rat skull was segregated, and enzyme digestion was used to obtain bone cells which were cultured in MEM containing 10% FBS. The medium was changed every three days, and serial subcultivation was performed when cells covered with 90% of the culture dish. The Osthol was added to 96-well plates with final concentration of 1 x 10(-4) mol/L, 1 x 10(-5) mol/L, 1 x l0(-6) mol/L and 1 x10(-7) mol/L, and MTT method was used to evaluate the proliferation. Differentiation analysis: the alkaline phosphatase (ALP) activity was determined at the 3rd, 6th, 9th, 12th and 15th days separately after osteogenic induction culture. The synthesis of type I collagen was observed using immunohistochemical method at the 8th day. The ALP stain was performed at the 12th day. The alizarin red staining was done and calcified nodules was counted at the 14th day. RESULTS: The Osthol with final concentration of 1 x 10(-4) mo/L inhibit the proliferation of ROB. The Osthol with final concentration of 1 x 10(-5) mol/L had no obvious influence on the proliferation of ROB, but it significantly promoted the activity of ALP, enhanced the synthesis of collagen type I and increased the number of calcified nodules. CONCLUSION: The Osthol with final concentration of 1 x 10(-5) mol/L can promote differentiation and maturation of ROB, which may be active ingredients of Chinese drugs for the osteoporosis prophylaxis.

[Comparative study on the osteogenic differentiation of rat bone marrow stromal cells effected by icariin and icariside II].

OBJECTIVE: To investigate the effects of icariin and it's main metabolites-icariside II on the osteogenic differentiation of rat bone marrow stromal cells (rBMSCs). METHODS: rBMSCs were cultured by adherence screening method, icariin and icariside II were supplemented into the culture at 5 x 10(-5) mol/L respectively. The osteogenic differentiation markers including alkaline phosphatase (ALP) activity, CFU-F(ALp), osteocalcin secretion, calcium deposition and mineralized bone modulus were compared among the icariin-supplemented group, icariside II and the control. The gene expressions of bFGF, IGF-1, Osterix and Runx-2 were examined by RT-Real Time PCR. RESULTS: Both icariside II and icariin significantly improved ALP activity, CFU-F(ALP) amount, osteocalcin secretion, calcium deposition and mineralized modulus. Besides, they enhanced the gene expressions of bFGF, IGF-1, Osterix and Runx-2. Icariside II was obviously stronger than icariin at the above activities. CONCLUSION: Icariside II is stronger than icariin at enhancing the osteogenic differentiation of rBMSCs, suggesting that icariin can be administered via oral and it's metabolites are the effective constitutes for antiosteoporosis activity.