Impaired osteoinduction in a rat model for chronic alcohol abuse

Photobiomodulation Therapy Improves Repair of Bone Defects Filled by Inorganic Bone Matrix and Fibrin Heterologous Biopolymer

Biomaterials are used extensively in graft procedures to correct bone defects, interacting with the body without causing adverse reactions. The aim of this pre-clinical study was to analyze the effects of photobiomodulation therapy (PBM) with the use of a low-level laser in the repair process of bone defects filled with inorganic matrix (IM) associated with heterologous fibrin biopolymer (FB). A circular osteotomy of 4 mm in the left tibia was performed in 30 Wistar male adult rats who were randomly divided into three groups: G1 = IM + PBM, G2 = IM + FB and G3 = IM + FB + PBM. PBM was applied at the time of the experimental surgery and three times a week, on alternate days, until euthanasia, with 830 nm wavelength, in two points of the operated site. Five animals from each group were euthanized 14 and 42 days after surgery. In the histomorphometric analysis, the percentage of neoformed bone tissue in G3 (28.4% ± 2.3%) was higher in relation to G1 (24.1% ± 2.91%) and G2 (22.2% ± 3.11%) at 14 days and at 42 days, the percentage in G3 (35.1% ± 2.55%) was also higher in relation to G1 (30.1% ± 2.9%) and G2 (31.8% ± 3.12%). In the analysis of the birefringence of collagen fibers, G3 showed a predominance of birefringence between greenish-yellow in the neoformed bone tissue after 42 days, differing from the other groups with a greater presence of red-orange fibers. Immunohistochemically, in all experimental groups, it was possible to observe immunostaining for osteocalcin (OCN) near the bone surface of the margins of the surgical defect and tartrate-resistant acid phosphatase (TRAP) bordering the newly formed bone tissue. Therefore, laser photobiomodulation therapy contributed to improving the bone repair process in tibial defects filled with bovine biomaterial associated with fibrin biopolymer derived from snake venom.

Deleterious effect of chronic high-dose ethanol intake on biomechanical bone properties and periodontal status

To evaluate the effect of high-graduation chronic ethanol (EtOH) intake on bone and periodontal tissues of rats. Male Wistar rats (250 g) were divided into two groups of n = 12 each one. EtOH (5 ml of 3 g/kg) was administered to the experimental group by gastric gavage twice a day for 20 days and the control group received water under the same conditions. The rats were euthanized and used to perform biochemical determination in plasma and gingival tissue, and histological and biomechanical studies in the femur and mandibular tissues. Alcohol increased both TNFα (p < 0.01) and PGE2 (p < 0.05) in plasma and gingiva (p < 0.05) as compared to controls. In addition, EtOH increased the alveolar bone loss as evidenced by the increased distance between the cement enamel junction and the alveolar crest (p < 0.01), the lower % of interradicular bone expressed as bone area/total area (B.Ar/T.Ar, p < 0.05) and the larger periodontal space (p < 0.05), as compared to controls. Likewise, the mandibular microtomographic analysis in alcoholized rats revealed a lower % of interradicular bone volume/total volume (BV/TV, p < 0.05), greater trabecular separation (p < 0.05) and greater % trabecular porosity (p < 0.05) than controls. No biomechanical alteration was observed in lower jaws, while the femur of alcoholized rats presented a decrease in the structural bone properties (p < 0.001), as a systemic consequence of deterioration of the diaphyseal architecture (p < 0.01) without changes in material properties. The consumption of high doses of alcohol produces deleterious effects on periodontal tissues that could be due not only to local but also systemic effects.

Alcohol-induced inhibition of bone formation and neovascularization contributes to the failure of fracture healing via the miR-19a-3p/FOXF2 axis

Aims

Alcoholism is a well-known detrimental factor in fracture healing. However, the underlying mechanism of alcohol-inhibited fracture healing remains poorly understood.

Methods

MicroRNA (miR) sequencing was performed on bone mesenchymal stem cells (BMSCs). The effects of alcohol and miR-19a-3p on vascularization and osteogenic differentiation were analyzed in vitro using BMSCs and human umbilical vein endothelial cells (HUVECs). An in vivo alcohol-fed mouse model of femur fracture healing was also established, and radiological and histomorphometric analyses were used to evaluate the role of miR-19a-3p. The binding of miR-19a-3p to forkhead box F2 (FOXF2) was analyzed using a luciferase reporter assay.

Results

miR-19a-3p was identified as one of the key regulators in the osteogenic differentiation of BMSCs, and was found to be downregulated in the alcohol-fed mouse model of fracture healing. In vitro, miR-19a-3p expression was downregulated after ethanol administration in both BMSCs and HUVECs. Vascularization and osteogenic differentiation were independently suppressed by ethanol and reversed by miR-19a-3p. In addition, the luciferase reporter assay showed that FOXF2 is the direct binding target of miR-19a-3p. In vivo, miR-19a-3p agomir stimulated callus transformation and improved the alcohol-impaired fracture healing.

Conclusion

This study is the first to demonstrate that the miR-19a-3p/FOXF2 axis has a pivotal role in alcohol-impaired fracture healing, and may be a potential therapeutic target.

Cite this article: Bone Joint Res 2022;11(6):386–397.

Effects of a Biocomplex Formed by Two Scaffold Biomaterials, Hydroxyapatite/Tricalcium Phosphate Ceramic and Fibrin Biopolymer, with Photobiomodulation, on Bone Repair

There are several treatment methods available for bone repair, although the effectiveness becomes limited in cases of large defects. The objective of this pre-clinical protocol was to evaluate the grafting of hydroxyapatite/tricalcium phosphate (BCP) ceramic biomaterial (B; QualyBone BCP^®, QualyLive, Amadora, Portugal) together with the heterologous fibrin biopolymer (FB; CEVAP/UNESP Botucatu, Brazil) and with photobiomodulation (PBM; Laserpulse^®, Ibramed, Amparo, Brazil) in the repair process of bone defects. Fifty-six rats were randomly divided into four groups of seven animals each: the biomaterial group (G1/B), the biomaterial plus FB group (G2/BFB); the biomaterial plus PBM group (G3/B + PBM), and the biomaterial plus FB plus PBM group (G4/BFB + PBM). After anesthesia, a critical defect was performed in the center of the rats’ parietal bones, then filled and treated according to their respective groups. The rats were euthanized at 14 and 42 postoperative days. Histomorphologically, at 42 days, the G4/BFB + PBM group showed a more advanced maturation transition, with more organized and mature bone areas forming concentric lamellae. A birefringence analysis of collagen fibers also showed a more advanced degree of maturation for the G4/BFB + PBM group. In the comparison between the groups, in the two experimental periods (14 and 42 days), in relation to the percentage of formation of new bone tissue, a significant difference was found between all groups (G1/B (5.42 ± 1.12; 21.49 ± 4.74), G2/BFB (5.00 ± 0.94; 21.77 ± 2.83), G3/B + PBM (12.65 ± 1.78; 29.29 ± 2.93), and G4/BFB + PBM (12.65 ± 2.32; 31.38 ± 2.89)). It was concluded that the use of PBM with low-level laser therapy (LLLT) positively interfered in the repair process of bone defects previously filled with the biocomplex formed by the heterologous fibrin biopolymer associated with the synthetic ceramic of hydroxyapatite and tricalcium phosphate.

Biological Behavior of Xenogenic Scaffolds in Alcohol-Induced Rats: Histomorphometric and Picrosirius Red Staining Analysis

In this experimental protocol, the objective was to evaluate the biological behavior of two xenogenic scaffolds in alcohol-induced rats through histomorphometric and Picrosirius Red staining analysis of non-critical defects in the tibia of rats submitted or not to alcohol ingestion at 25% v/v. Eighty male rats were randomly divided into four groups (n = 20 each): CG/B (water diet + Bio-Oss^® graft, Geistlich Pharma AG, Wolhusen, Switzerland), CG/O (water diet + OrthoGen^® graft, Baumer, Mogi Mirim, Brazil), AG/B (25% v/v alcohol diet + Bio-Oss^® graft), and AG/O (25% v/v alcohol diet + OrthoGen^® graft). After 90 days of liquid diet, the rats were surgically obtained, with a defect in the tibia proximal epiphysis; filled in according to their respective groups; and euthanized at 10, 20, 40 and 60 days. In two initial periods (10 and 20 days), all groups presented biomaterial particles surrounded by disorganized collagen fibrils. Alcoholic animals (AG/B and AG/O) presented, in the cortical and medullary regions, a reactive tissue with inflammatory infiltrate. In 60 days, in the superficial area of the surgical cavities, particles of biomaterials were observed in all groups, with new compact bone tissue around them, without complete closure of the lesion, except in non-alcoholic animals treated with Bio-Oss^® xenograft (CG/B), where the new cortical interconnected the edges of the defect. Birefringence transition was observed in the histochemical analysis of collagen fibers by Picrosirius Red, in which all groups in periods of 10 and 20 days showed red-orange birefringence, and from 40 days onwards greenish-yellow birefringence, which demonstrates the characteristic transition from the formation of thin and disorganized collagen fibers initially to more organized and thicker later. In histomorphometric analysis, at 60 days, CG/B had the highest volume density of new bone (32.9 ± 1.15) and AG/O the lowest volume density of new bone (15.32 ± 1.71). It can be concluded that the bone neoformation occurred in the defects that received the two biomaterials, in all periods, but the Bio-Oss^® was superior in the results, with its groups CG/B and AG/B displaying greater bone formation (32.9 ± 1.15 and 22.74 ± 1.15, respectively) compared to the OrthoGen^® CG/O and AG/O groups (20.66 ± 2.12 and 15.32 ± 1.71, respectively), and that the alcoholic diet interfered negatively in the repair process and in the percentage of new bone formed.

Toxicological Analysis of Hepatocytes Using FLIM Technique: In Vitro versus Ex Vivo Models

The search for new criteria indicating acute or chronic pathological processes resulting from exposure to toxic agents, testing of drugs for potential hepatotoxicity, and fundamental study of the mechanisms of hepatotoxicity at a molecular level still represents a challenging issue that requires the selection of adequate research models and tools. Microfluidic chips (MFCs) offer a promising in vitro model for express analysis and are easy to implement. However, to obtain comprehensive information, more complex models are needed. A fundamentally new label-free approach for studying liver pathology is fluorescence-lifetime imaging microscopy (FLIM). We obtained FLIM data on both the free and bound forms of NAD(P)H, which is associated with different metabolic pathways. In clinical cases, liver pathology resulting from overdoses is most often as a result of acetaminophen (APAP) or alcohol (ethanol). Therefore, we have studied and compared the metabolic state of hepatocytes in various experimental models of APAP and ethanol hepatotoxicity. We have determined the potential diagnostic criteria including the pathologically altered metabolism of the hepatocytes in the early stages of toxic damage, including pronounced changes in the contribution from the bound form of NAD(P)H. In contrast to the MFCs, the changes in the metabolic state of hepatocytes in the ex vivo models are, to a greater extent, associated with compensatory processes. Thus, MFCs in combination with FLIM can be applied as an effective tool set for the express modeling and diagnosis of hepatotoxicity in clinics.

Chronic cachaça consumption affects the structure of tibial bone by decreasing bone density and density of mature collagen fibers in middle-aged Wistar rats

Several studies have demonstrated that alcohol consumption can decrease bone density and alter its structure. However, most of the studies did not investigate the effects of specific alcoholic beverages. This study determined the effects of chronic consumption of cachaça (a Brazilian beverage containing alcohol) on body weight (BW), tibia bone density and on the tibia collagen density in middle-aged Wistar rats. Rats with 9 months old were submitted for 100 days, to a liquid diet of cachaça diluted in water with a progressive and controlled concentration (10°GL, 15°GL, 20°GL, 25°GL, and 30°GL). Chronic cachaça intake produced a significant decrease in BW and altered bone remodeling, decreasing trabecular bone density. In chronic cachaça-treated group (CT), the production of collagen fibers in bone tissue has predominantly green birefringence. It appears that they are immature fibers that do not exist in the control group, in which there are standard predominantly yellowish mature fibers. In conclusion, chronic cachaça consumption affects the structure of the tibial bone of middle-aged rats by decreasing the bone density and reducing the density of mature collagen fibers.

Antagonistic Impact of Acrylamide and Ethanol on Biochemical and Morphological Parameters Consistent with Bone Health in Mice

Simple Summary

Alcohol consumption, the drinking of beverages containing ethanol, represents a growing problem worldwide. Alcohol intake is often combined with an improper diet based on highly processed starch products that are rich in acrylamide. Both acrylamide and alcohol have a harmful impact on bone health. We previously demonstrated that adverse effects of ethanol on cortical bone structure were partly reduced by a relatively high dose of acrylamide in mice after one remodelling cycle. The present research was designated to reveal whether the antagonistic impact of both aforementioned toxins can also be achieved using a lower dose of acrylamide. According to our results, individual administrations of acrylamide and ethanol had adverse impacts on biochemical and morphological parameters consistent with bone health in mice. However, the most detrimental effects of ethanol were again alleviated by acrylamide at the dose used in this study.

Abstract

The aim of present study was to verify antagonistic effect of acrylamide (AA) and ethanol (Et) on bone quality parameters. Adult mice (n = 20) were segregated into four groups following 2 weeks administration of toxins: group E1, which received AA (20 mg/kg body weight daily); group E2, which received 15% Et (1.7 g 100% Et/kg body weight daily); group E12, which received simultaneously both toxins; and a control group. An insignificant impact of individual applications of AA, Et or their simultaneous supplementation on the total body weight of mice and the length and weight of their femoral bones was identified. In group E1, higher levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), a decreased level of glutathione (GSH) and elevated endocortical bone remodelling were determined. A significantly lower relative volume of cortical bone, bone mineral density (BMD), elevated endocortical bone remodelling and cortical porosity, higher levels of ALT, AST, lower values for total proteins (TP), GSH, alkaline phosphatase (ALP), calcium, and phosphorus were recorded in group E2. In the mice from group E12, the highest endocortical bone remodelling, decreased values for BMD, TP, GSH and ALP and increased levels of ALT and AST were found. Our findings confirmed the antagonistic impact of AA and Et at doses used in this study on biochemical and morphological parameters consistent with bone health in an animal model.

The Antagonist of Retinoic Acid Receptor α, ER-50891 Antagonizes the Inhibitive Effect of All-Trans Retinoic Acid and Rescues Bone Morphogenetic Protein 2-Induced Osteoblastogenic Differentiation

Background

Hypervitaminosis A, alcoholism or medical treatment for acute promyelocytic leukaemia may cause unphysiologically high accumulation of all-trans retinoic acid (ATRA), which could inhibit osteoblastogenesis, thereby triggering osteoporosis. We have shown that bone morphogenetic protein-2 (BMP-2) can only partially antagonize the inhibitive effects of ATRA. In this study, we hypothesized that antagonists of retinoic acid receptors (RARs) could further antagonize the inhibitive effect of ATRA and rescue BMP2-induced osteoblastogenesis.

Materials and Methods

We first screened the dose-dependent effects of the specific antagonists of RAR α, β and γ and transforming growth factor-beta receptor (ER-50891, LE-135, MM11253, and SB-43142, respectively) on ATRA-induced inhibition of the total cell metabolic activity and proliferation of preosteoblasts. We selected ER-50891 and tested its effects on osteoblastogenesis with the presence or absence of 1 μM ATRA and/or 200 ng/mL BMP-2. We measured the following parameters: Alkaline phosphatase activity (ALP), osteocalcin (OCN) expression and extracellular matrix mineralization as well as the level of phosphorylated Smad1/5.

Results

ER-50891 but not LE-135, MM11253, or SB-431542 significantly antagonized the inhibition of ATRA and enhanced the total cell metabolic activity and proliferation of preosteoblasts. Dose-dependent assays show ER-50891 could also rescue ATRA inhibited OCN expression and mineralization with or without the induction of BMP. ER-50891 also suppressed the ALP activity that was synergistically enhanced by BMP and ATRA. Neither ATRA, nor ER-50891 or their combination significantly affected the level of BMP-induced phosphorylated Smad1/5.

Conclusion

The antagonist of RARα, ER-50891 could significantly attenuate ATRA’s inhibitive effects on BMP 2-induced osteoblastogenesis.

Role of Nrf2 in Fracture Healing: Clinical Aspects of Oxidative Stress

Fracture healing is a natural process that recapitulates embryonic skeletal development. In the early phase after fracture, reactive oxygen species (ROS) are produced under inflammatory and ischemic conditions due to vessel injury and soft tissue damage, leading to cell death. Usually, such damage during the course of fracture healing can be largely prevented by protective mechanisms and functions of antioxidant enzymes. However, intrinsic oxidative stress can cause excessive toxic radicals, resulting in irreversible damage to cells associated with bone repair during the fracture healing process. Clinically, patients with type-2 diabetes mellitus, osteoporosis, habitual drinkers, or heavy smokers are at risk of impaired fracture healing due to elevated oxidative stress. Although increased levels of oxidative stress markers upon fracture and effects of antioxidants on fracture healing have been reported, a detailed understanding of what causes impaired fracture healing under intrinsic conditions of oxidative stress is lacking. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been identified as a key transcriptional regulator of the expression of antioxidants and detoxifying enzymes. It further not only plays a crucial role in preventing degenerative diseases in multiple organs, but also during fracture healing. This narrative review evaluates the influence of intrinsic oxidative stress on fracture healing and sheds new light on the intriguing role of Nrf2 during bone regeneration in pathological fractures.

Exosomes in the Repair of Bone Defects: Next-Generation Therapeutic Tools for the Treatment of Nonunion

Nonunion with bone defects, a common complication after long bone fracture, is a major challenge for orthopaedic surgeons worldwide because of the high incidence rate and difficulties in achieving successful treatment. Bone defects are the main complications of nonunion. The conventional biological treatments for nonunion with bone defects involve the use of autologous bone grafts or bone graft substitutes and cell-based therapy. Traditional nonunion treatments have always been associated with safety issues and various other complications. Bone grafts have limited autologous cancellous bone and there is a risk of infection. Additionally, problems with bone graft substitutes, including rejection and stimulation of bone formation, have been noted, and the health of the stem cell niche is a major consideration in cell-based therapy. In recent years, researchers have found that exosomes can be used to deliver functional RNA and mediate cell-to-cell communication, suggesting that exosomes may repair bone defects by regulating cells and cytokines involved in bone metabolism. In this review, we highlight the possible relationships between risk factors for nonunion and exosomes. Additionally, we discuss the roles of exosomes in bone metabolism and bone regeneration.

Single and simultaneous effects of acrylamide and ethanol on bone microstructure of mice after one remodeling cycle

Background

This study aimed to examine femoral bone microstructure of mice after single and simultaneous administration to acrylamide and ethanol since both substances are often consumed separately and/or together by humans. Interactive effects of these toxins were analysed after one remodeling cycle.

Methods

Twenty clinically healthy adult mice were randomly divided into four groups following 2 weeks administration of toxins: A group - mice were fed with acrylamide (40 mg/kg bw); E group - mice were ethanol-fed (15% ethanol); AE group - mice were simultaneously fed with both toxins, and a C group – control (without acrylamide and/or ethanol supplementation). Generally, 2D and 3D imaging methods were used to determine cortical and trabecular bone tissues microstructure. Biochemical analyses of plasma parameters were also realized using commercially available ELISA tests and spectrophotometrically.

Results

Single and simultaneous exposure to acrylamide and ethanol affected only cortical bone microstructure. No significant changes in trabecular bone morphometry were detected among all groups. In mice from the A group, increased endocortical remodeling associated with a higher level of serum calcium and vasoconstriction of primary osteon’s vascular canals (POVC) were identified. On the contrary, increased cortical porosity consistent with a decreased relative bone volume, bone mineral density (BMD) and lower levels of alkaline phosphatase (ALP), glutathione (GSH), calcium in plasma and also with vasodilation of POVC were observed in the E group. In the AE group, the highest density of secondary osteons associated with a lower BMD and decreased levels of ALP, GSH were documented. The parameters of POVC and Haversian canals approximated to the C group. In addition, single and simultaneous exposure to both toxins caused liver disease consistent with a higher values of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in plasma of all experimental groups.

Conclusions

Single administration to acrylamide and ethanol had negative effects on cortical bone structure of mice after one remodeling cycle. However, we identified possible antagonistic impact of these toxins on the structure of the cortical bone.

Influence of experimental alcoholism on the repair process of bone defects filled with beta-tricalcium phosphate

This study evaluated the effect of ethanol on the repair in calvaria treated with beta-tricalcium phosphate (β-TCP). Forty rats were distributed into 2 groups: Water group (CG, n = 20) and Alcohol Group (AG, n = 20), which received 25% ethanol ad libitum after an adaptation period of 3 weeks. After 90 days of liquid diet, the rats were submitted to a 5.0 mm bilateral craniotomy in the parietal bones; the left parietal was filled with β-TCP (CG-TCP and AG-TCP) and the contralateral only with blood clot (CG-Clot and AG-Clot). The animals were killed after 10, 20, 40 and 60 days. The groups CG-Clot and AG-Clot showed similar pattern of bone formation with a gradual and significant increase in the amount of bone in CG-Clot (22.17 ± 3.18 and 34.81 ± 5.49) in relation to AG-Clot (9.35 ± 5.98 and 21.65 ± 6.70) in periods of 20-40 days, respectively. However, in the other periods there was no statistically significant difference. Alcohol ingestion had a negative influence on bone formation, even with the use of β-TCP, exhibiting slow resorption and replacement by fibrous tissue, with 16% of bone formation within 60 days in AG-TCP, exhibiting immature bone tissue with predominance of disorganized collagen fibers. Defects in CG-TCP showed bone tissue with predominance of lamellar arrangement filling 39% of the original defect. It can be concluded that chronic ethanol consumption impairs the ability to repair bone defects, even with the use of a β-TCP biomaterial.

Changes in the microstructure of compact and trabecular bone tissues of mice subchronically exposed to alcohol

BACKGROUND

Alcohol is one of the most commonly consumed neurotoxins by humans. Its negative effect on bone health is known for a long time. However, its impact on qualitative and quantitative 2D characteristics of the compact bone is still unclear. Therefore, the aim of this study was to investigate in detail the effects of subchronic alcohol exposure on compact and trabecular bone tissues microstructure of laboratory mice using 2D and 3D imaging methods. Ten clinically healthy 12 weeks-old mice (males) were randomly divided into two groups. Animals from experimental group (group E; n = 5) drank a solution composed of 15% ethanol and water (1.7 g 100% ethanol kg-1 b.w. per day) for 8 weeks, while those from control group (group C; n = 5) drank only water.

RESULTS

Subchronic exposure to alcohol leads to several changes in qualitative 2D characteristics of the compact bone such as the presence of primary vascular radial bone tissue in pars anterior of endosteal border and a higher number of resorption lacunae (five times more) in the middle part of substantia compacta. Morphometrical 2D evaluations of the compact bone showed significantly increased sizes of primary osteons' vascular canals (p < 0.05) in mice from the experimental group (E group). Sizes of Haversian canals and secondary osteons were not affected by alcohol consumption. In mice from the E group, significantly lower values for relative bone volume and bone mineral density of the compact bone were observed. In the trabecular bone, decreased values for bone volume, trabecular number, trabecular thickness and bone surface (p < 0.05) were documented.

CONCLUSIONS

Alcohol decreased not only bone volume and density of the compact bone, but it also reduced trabecular bone volume and leads to trabecular thinning. It caused vasodilation of primary osteons' vascular canals and increased porosity in the compact bone.

All-trans retinoic acid can antagonize osteoblastogenesis induced by different BMPs irrespective of their dimerization types and dose-efficiencies

Introduction

Alcoholism can lead to low mineral density, compromised regenerative bone capacity and delayed osteointegration of dental implants. This may be partially attributed to the inhibitive effect of all-trans retinoic acid (ATRA), a metabolite of alcohol, on osteoblastogenesis. Our previous studies demonstrated that heterodimeric bone morphogenetic protein 2/7 (BMP2/7) was a more potent BMP than homodimeric BMP2 or BMP7, and could antagonize the inhibitive effect of ATRA to rescue osteoblastogenesis.

Materials and methods

In this study, we compared the effectiveness of BMP2/7, BMP2 and BMP7 in restoring osteoblastogenesis of murine preosteoblasts upon inhibition with 1 µM ATRA, and we further analyzed the potential mechanisms. We measured the following parameters: cell viability, ALP, OCN, mineralization, the expression of osteogenic differentiation marker genes (Collagen I, ALP and OCN) and the expression of BMP signaling key genes (Dlx5, Runx2, Osterix and Smad1).

Results

BMP2/7 treatment alone induced significantly higher osteoblastogenesis compared to BMP2 and BMP7. When cells were treated by ATRA, BMP2/7 was superior only in rescuing cell viability and ALP activity, compared to BMP2 or BMP7. However, BMP2/7 was not superior to BMP2 or BMP7 in restoring OCN expression and extracellular mineralized nodules, or in rescuing expression of two key osteogenic genes, Dlx5 and Runx2. Irrespective of their dimeric types or potency, the selected BMPs could antagonize the inhibitory effect of ATRA on osteoblastogenesis.

Conclusion

The presence of ATRA, BMP2/7 still induced significantly higher cell viability and early differentiation than the homodimers. However, ATRA significantly attenuated the advantages of BMP2/7 in inducing late and final osteoblastogenic differentiation over the homodimers.

Subacute exposure to alcohol in relation to bone microstructure of mice

Our study aimed to investigate subacute exposure to alcohol in relation to bone microstructure of mice. Animals from experimental (E) group drank a solution composed of 15 % ethanol and water for 14 days (one remodeling cycle), while those from control (C) group drank only water. In the compact bone of E group, decreased bone formation and increased porosity were observed which corresponds with lower levels of serum alkaline phosphatase and glutathione. Alcohol significantly increased sizes of primary osteon's vascular canals and decreased those of secondary osteons, Haversian canals. Relative bone volume, bone mineral density (BMD), relative bone volume without marrow cavity were also lower in E group. On the contrary, trabecular bone microstructure did not differ significantly between E and C groups. Liver function test showed higher levels of alanine aminotransferase, aspartate aminotransferase in alcohol-fed mice. Serum calcium, phosphate were significantly lower in E group. According to our study, only changes in compact bone microstructure of mice following one remodeling cycle were observed due to both direct and indirect effects of alcohol.

The Effect of Opioids, Alcohol, and Nonsteroidal Anti-inflammatory Drugs on Fracture Union

The estimated rate of fracture nonunion is between 5% and 10%, adding significant cost to the health care system. The cause of fracture nonunion is multifactorial, including the severity of the injury, patient factors resulting in aberrancies in the biology of fracture, and the side effects of pain control modalities. Minimizing surgeon-controlled factors causing nonunion is important to reduce the cost of health care and improve patient outcomes. Opioids, alcohol, and nonsteroidal anti-inflammatory drugs have been implicated as risk factors for fracture nonunion. Current literature was reviewed to examine the effects of opioids, alcohol, and nonsteroidal anti-inflammatory drugs on fracture union.

Alcohol: A Simple Nutrient with Complex Actions on Bone in the Adult Skeleton

BACKGROUND

Alcohol is an important nonessential component of diet, but the overall impact of drinking on bone health, especially at moderate levels, is not well understood. Bone health is important because fractures greatly reduce quality of life and are a major cause of morbidity and mortality in the elderly. Regular alcohol consumption is most common following skeletal maturity, emphasizing the importance of understanding the skeletal consequences of drinking in adults.

METHODS

This review focuses on describing the complex effects of alcohol on the adult skeleton. Studies assessing the effects of alcohol on bone in adult humans as well as skeletally mature animal models published since the year 2000 are emphasized.

RESULTS

Light to moderate alcohol consumption is generally reported to be beneficial, resulting in higher bone mineral density (BMD) and reduced age-related bone loss, whereas heavy alcohol consumption is generally associated with decreased BMD, impaired bone quality, and increased fracture risk. Bone remodeling is the principal mechanism for maintaining a healthy skeleton in adults and dysfunction in bone remodeling can lead to bone loss and/or decreased bone quality. Light to moderate alcohol may exert beneficial effects in older individuals by slowing the rate of bone remodeling, but the impact of light to moderate alcohol on bone remodeling in younger individuals is less certain. The specific effects of alcohol on bone remodeling in heavy drinkers are even less certain because the effects are often obscured by unhealthy lifestyle choices, alcohol-associated disease, and altered endocrine signaling.

CONCLUSIONS

Although there have been advances in understanding the complex actions of alcohol on bone, much remains to be determined. Limited evidence implicates age, skeletal site evaluated, duration, and pattern of drinking as important variables. Few studies systematically evaluating the impact of these factors have been conducted and should be made a priority for future research. In addition, studies performed in skeletally mature animals have potential to reveal mechanistic insights into the precise actions of alcohol and associated comorbidity factors on bone remodeling.

Effects of chronic heavy alcohol consumption and endurance exercise on cancellous and cortical bone microarchitecture in adult male rats

BACKGROUND

Bone health is influenced by numerous lifestyle factors, including diet and exercise. Alcohol is a major nonessential constituent of diet and has dose- and context-dependent effects on bone. Endurance exercise is associated with increased risk of stress fractures. The purpose of this study was to determine the long-term independent and combined effects of chronic heavy alcohol consumption and endurance exercise (treadmill running) on bone mass and microarchitecture in young adult male Sprague-Dawley rats.

METHODS

Six-month-old male rats were randomized into 4 groups (9 to 13 rats/group): sedentary + control diet, sedentary + ethanol (EtOH) diet, exercise + control diet, or exercise + EtOH diet. EtOH-fed rats consumed a liquid diet (EtOH comprised 35% of caloric intake) ad libitum. Control rats were pair-fed the same diet with isocaloric substitution of EtOH with maltose-dextran. Exercise was conducted on a motorized treadmill (15% grade for 30 minutes) 5 d/wk for 16 weeks. Femur and 12th thoracic vertebra were analyzed for bone mineral content (BMC) and density (BMD) using densitometry and cortical and cancellous bone architecture using microcomputed tomography.

RESULTS

EtOH consumption resulted in lower femur length, BMC, and BMD, and lower midshaft femur cortical volume, cortical thickness, and polar moment of inertia. In addition, trabecular thickness was lower in vertebra of EtOH-fed rats. Endurance exercise had no independent effect on any end point evaluated. A significant interaction between endurance exercise and EtOH was detected for several cancellous end points in the distal femur metaphysis. EtOH-consuming rats that exercised had lower distal femur metaphysis bone volume/tissue volume, trabecular connectivity density, and trabecular thickness compared to exercising rats that consumed control diet.

CONCLUSIONS

The results obtained in this model suggest that chronic heavy alcohol consumption may reduce skeletal integrity by reducing bone size, mass, and density, and by negatively altering bone microarchitecture and may increase fracture risk associated with endurance exercise at weight-bearing skeletal sites.

Alcohol and bone

Alcohol is widely consumed across the world in different cultural and social settings. Types of alcohol consumption differ between (a) light, only occasional consumption, (b) heavy chronic alcohol consumption, and (c) binge drinking as seen as a new pattern of alcohol consumption among teenagers and young adults. Heavy alcohol consumption is detrimental to many organs and tissues, including bones. Osteoporosis is regularly mentioned as a secondary consequence of alcoholism, and chronic alcohol abuse is established as an independent risk factor for osteoporosis. The review will present the different mechanisms and effects of alcohol intake on bone mass, bone metabolism, and bone strength, including alcoholism-related "life-style factors" such as malnutrition, lack of exercise, and hormonal changes as additional causative factors, which also contribute to the development of osteoporosis due to alcohol abuse.

Heterodimeric BMP-2/7 antagonizes the inhibition of all-trans retinoic acid and promotes the osteoblastogenesis

Objectives

Hypervitaminosis A and alcoholism can result in a low mineral density and compromised regenerative capacity of bone, thus delaying implant osteointegration. The inhibitory effect of all-trans retinoic acid on osteoblastogenesis is considered to be one of the mechanisms. We hypothesized that heterodimeric bone morphogenetic protein-2/7 could antagonize all-trans retinoic acid and enhance osteoblastogenesis, with an aim to accelerate and enhance bone regeneration and implant osteointegration.

Materials and Methods

We applied 5 ng/ml or 50 ng/ml bone morphogenetic protein-2/7 to restore the osteoblastogenesis of pre-osteoblasts (MC3T3-E1 cell line) that was inhibited by 1 µM all-trans retinoic acid. We evaluated the efficacy by assessing cell numbers (proliferation), alkaline phosphatase activity (a marker for early differentiation), osteocalcin (a marker for late differentiation), calcium deposition (a marker for final mineralization) and the expression of osteoblastogenic genes (such as Runx2, Collagen Ia, alkaline phosphatase and osteocalcin) at different time points.

Results

All-trans retinoic acid significantly inhibited the expression of all the tested osteoblastogenic genes and proteins except alkaline phosphatase activity. In the presence of ATRA, 50 ng/ml bone morphogenetic protein-2/7 not only completely restored but also significantly enhanced all the osteoblastogenic genes and proteins. On the 28^th day, mineralization was completely inhibited by all-trans retinoic acid. In contrast, 50 ng/ml BMP-2/7 could antagonize ATRA and significantly enhance the mineralization about 2.5 folds in comparison with the control treatment (no ATRA, no BMP2/7).

Conclusions

Heterodimeric bone morphogenetic protein-2/7 bears a promising application potential to significantly promote bone regeneration and implant osteointegration for the patients with hypervitaminosis A and alcoholism.

Acute alcohol exposure impairs fracture healing and deregulates β-catenin signaling in the fracture callus

BACKGROUND

Alcohol abuse is a risk factor for bone damage and fracture-related complications. Through precise β-catenin signaling, canonical Wnt signaling plays a key role in fracture repair by promoting the differentiation of new bone and cartilage cells. In this study, we examined the effects of alcohol on the Wnt pathway in injured bone using a murine model of alcohol-induced impaired fracture healing.

METHODS

Male C57Bl/6 or T cell factor (TCF)-transgenic mice were administered 3 daily intraperitoneal doses of alcohol or saline. One hour following the final injection, mice were subjected to a stabilized, mid-shaft tibial fracture. Injured and contralateral tibias were harvested at 6, 9, or 14 days post-fracture for the analysis of biomechanical strength, callus tissue composition, and Wnt/β-catenin signaling.

RESULTS

Acute alcohol treatment was associated with a significant decrease in fracture callus volume, diameter, and biomechanical strength at day 14 post-fracture. Histology revealed an alcohol-related reduction in cartilage and bone formation at the fracture site, and that alcohol inhibited normal cartilage maturation. Acute alcohol exposure caused a significant 2.3-fold increase in total β-catenin protein at day 6 and a significant decrease of 53 and 56% at days 9 and 14, respectively. lacZ staining in β-galactosidase-expressing TCF-transgenic mice revealed spatial and quantitative differences in Wnt-specific transcriptional activation at day 6 in the alcohol group. Days 9 and 14 post-fracture showed that acute alcohol exposure decreased Wnt transcriptional activation, which correlates with the modulation of total β-catenin protein levels observed at these time points.

CONCLUSIONS

Acute alcohol exposure resulted in significant impairment of fracture callus tissue formation, perturbation of the key Wnt pathway protein β-catenin, and disruption of normal Wnt-mediated transcription. These data suggest that the canonical Wnt pathway is a target for alcohol in bone and may partially explain why impaired fracture healing is observed in alcohol-abusing individuals.

Alcohol and bone: review of dose effects and mechanisms

Alcohol is widely consumed across the world. It is consumed in both social and cultural settings. Until recently, two types of alcohol consumption were recognized: heavy chronic alcohol consumption or light consumption. Today, there is a new pattern of consumption among teenagers and young adults namely: binge drinking. Heavy alcohol consumption is detrimental to many organs and tissues, including bones, and is known to induce secondary osteoporosis. Some studies, however, have reported benefits from light alcohol consumption on bone parameters. To date, little is known regarding the effects of binge drinking on bone health. Here, we review the effects of three different means of alcohol consumption: light, heavy, and binge drinking. We also review the detailed literature on the different mechanisms by which alcohol intake may decrease bone mass and strength. The effects of alcohol on bone are thought to be both direct and indirect. The decrease in bone mass and strength following alcohol consumption is mainly due to a bone remodeling imbalance, with a predominant decrease in bone formation. Recent studies, however, have reported new mechanisms by which alcohol may act on bone remodeling, including osteocyte apoptosis, oxidative stress, and Wnt signalling pathway modulation. The roles of reduced total fat mass, increased lipid content in bone marrow, and a hypoleptinemia are also discussed.

Alcohol induced epigenetic perturbations during the inflammatory stage of fracture healing

It is well recognized by orthopedic surgeons that fractures of alcoholics are more difficult to heal successfully and have a higher incidence of non-union, but the mechanism of alcohol's effect on fracture healing is unknown. In order to give direction for the study of the effects of alcohol on fracture healing, we propose to identify gene expression and microRNA changes during the early stages of fracture healing that might be attributable to alcohol consumption. As the inflammatory stage appears to be the most critical for successful fracture healing, this paper focuses on the events at day three following fracture or the stage of inflammation. Sprague-Dawley rats were placed on an ethanol-containing or pair-fed Lieber and DeCarli diet for four weeks prior to surgical fracture. Following insertion of a medullary pin, a closed mid-diaphyseal fracture was induced using a Bonnarens and Einhorn fracture device. At three days' post-fracture, the region of the fracture calluses was harvested from the right hind-limb. RNA was extracted and microarray analysis was conducted against the entire rat genome. There were 35 genes that demonstrated significant increased expression due to alcohol consumption and 20 that decreased due to alcohol. In addition, the expression of 20 microRNAs was increased and six decreased. In summary, while it is recognized that mRNA levels may or may not represent protein levels successfully produced by the cell, these studies reveal changes in gene expression that support the hypothesis that alcohol consumption affects events involved with inflammation. MicroRNAs are known to modulate mRNA and these findings were consistent with much of what was seen with mRNA microarray analysis, especially the involvement of smad4 which was demonstrated by mRNA microarray, microRNA and polymerase chain reaction.

Harmful lifestyles on orthopedic implantation surgery: a descriptive review on alcohol and tobacco use

Alcohol abuse and smoking habits have adverse effects on bone health and are a risk factor for osteoporosis, fractures and impaired fracture repair. Osteointegration processes around implanted biomaterials involve a coordinated cascade of complex events that are very similar to those occurring during fracture repair and require a suitable microenvironment and the coordinated action of cells and signal molecules. Therefore, diseases and harmful lifestyles that impair the normal bone healing process can reduce the success of implant surgery and may negatively influence the osteointegration of prostheses and implant devices for fracture fixation such as screws, nails and plates. Understanding the effects of harmful lifestyles on bone implant osteointegration is important for successful implant therapy, orthopedic reconstructive surgery and tissue-engineered-based therapies. However, the mechanisms by which smoking and alcoholism affect bone metabolism, bone mass and the balance of bone resorption and formation, also in the presence of an orthopedic implant, are not completely understood and remain inadequately elucidated. This review aims to analyze in vitro and in vivo studies regarding orthopedic implant integration in the presence of tobacco smoking and alcohol consumption with a focus on pathophysiology and local or systemic mechanisms of action on bone.

Antioxidant therapy attenuates deficient bone fracture repair associated with binge alcohol exposure

OBJECTIVES

Alcohol consumption is a known risk factor for traumatic injuries of all types and has been shown to produce detrimental effects on bone metabolism. Although the mechanisms responsible for these detrimental effects are not well characterized, oxidative stress from alcohol exposure appears to play a central role. This study was designed to examine the effect of a short-term binge alcohol consumption pattern on fracture repair and the effect of an antioxidant, N-acetylcysteine, on fracture healing after binge alcohol consumption.

METHODS

One hundred forty-four adult male Sprague-Dawley rats underwent unilateral closed femur fracture after injection of either saline or alcohol to simulate a binge alcohol cycle. Animals in the antioxidant treatment group received daily N-acetylcysteine after fracture. Femurs were harvested at 1, 2, 4, and 6 weeks after injury and underwent biomechanical testing and histologic analysis.

RESULTS

Binge alcohol administration was associated with significant decreases in biomechanical strength at 1- and 2-week time points with a trend toward decreased strength at 4- and 6-week time points as well. Alcohol-treated animals had less cartilage component within the fracture callus and healed primarily by intramembranous ossification. Administration of N-acetylcysteine in alcohol-treated animals improved biomechanical strength to levels comparable to the control animals and was associated with increased endochondral ossification.

CONCLUSIONS

Our results indicate that binge alcohol alters the quality of fracture healing after a traumatic injury and that concurrent administration of an antioxidant is able to reverse these effects.

Impaired expansion and multipotentiality of adult stromal cells in a rat chronic alcohol abuse model

It is well established that bone maintenance and healing is compromised in alcoholics. Adult bone marrow-derived stromal cells (BMSCs) and adipose tissue-derived stromal cells (ASCs) likely contribute to bone homeostasis and formation. Direct and indirect alcohol exposure inhibits osteoprogenitor cell function through a variety of proposed mechanisms. The goal of this study was to characterize the effects of chronic alcohol ingestion on the native number and in vitro growth characteristics and multipotentiality of adult BMSCs and ASCs in a rat model. Adult male Sprague-Dawley rats received a liquid diet containing 36% ethanol or an isocaloric substitution of dextramaltose (control). After 4, 8, or 12 weeks of the diet, ASCs were harvested from epididymal adipose tissue and BMSCs from femoral and tibial bone marrow. Cell doublings (CDs) per day and doubling times (DTs) were determined for primary cells (P0) and cell passages 1 through 6 (P1-P6). Fibroblastic (CFU-F), adipogenic (CFU-Ad), and osteogenic (CFU-Ob) colony-forming unit (CFU) frequencies were assessed for P0, P3, and P6. The CDs and DTs were lower and higher, respectively, for ASCs and BMSCs harvested from ethanol versus control rats at all time points. The CFU-F, CFU-Ad, and CFU-Ob were significantly higher in ASCs harvested from control versus ethanol rats for P0, P3, and P6 at all times. Both CFU-Ad and CFU-Ob were significantly higher in P0 BMSCs harvested from control versus ethanol rats after 12 weeks of the diet. The CFU-Ob for P3 BMSCs from control rats was significantly higher than those from ethanol rats after 8 and 12 weeks on the diet. All three CFU frequencies in ASCs from ethanol rats tended to decrease with increasing diet duration. The ASC cell and colony morphology was different between control and ethanol cohorts in culture. These results emphasize the significant detrimental effects of chronic alcohol ingestion on the in vitro expansion and multipotentiality of adult mesenchymal stromal cells (MSCs). Maintenance of the effects through multiple cell passages in vitro suggests cells may be permanently compromised.

Alcohol exposure and mechanisms of tissue injury and repair

Tissue injury owing to acute and chronic alcohol consumption has extensive medical consequences, with the level and duration of alcohol exposure affecting both the magnitude of injury and the time frame to recovery. While the understanding of many of the molecular processes disrupted by alcohol has advanced, mechanisms of alcohol-induced tissue injury remain a subject of intensive research. Alcohol has multiple targets, as it affects diverse cellular and molecular processes. Some mechanisms of tissue damage as a result of alcohol may be common to many tissue types, while others are likely to be tissue specific. Here, we present a discussion of the alcohol-induced molecular and cellular disruptions associated with injury or recovery from injury in bone, muscle, skin, and gastric mucosa. In every case, the goal of characterizing the sites of alcohol action is to devise potential measures for protection, prevention, or therapeutic intervention.

Direct chemical cross-linking of platelet-derived growth factor-BB to the demineralized bone matrix improves cellularization and vascularization

In previous studies, we have described the use of demineralized bone matrix (DBM) as a carrier for the localized delivery system of growth factors in vitro and in vivo. The aim of the present work was to develop a direct chemical approach to immobilize the platelet-derived growth factor-BB (PDGF-BB) on DBM with cross-linking reagents. The amount of PDGF-BB covalently immobilized on DBM was significantly increased. The increased proliferation of fibroblasts demonstrated that the biological activity of PDGF-BB was not significantly reduced by cross-linking. Compared with control groups, there was a statistically significant increase in blood vessel density in the PDGF-C-DBM group after having been subcutaneously implanted into the dorsal side of the rats. The surface bioactivity of scaffolds on stimulation cell and new blood vessel invasion was improved. Therefore, the direct chemical cross-linking approach could be used to retain growth factors on collagen scaffolds effectively to develop functional biomaterials.

Loading of VEGF to the heparin cross-linked demineralized bone matrix improves vascularization of the scaffold

Deficient vascularization is one of the prominent shortcomings of porous tissue-engineering scaffolds, which results in insufficient oxygen and nutrients transportation. Here, heparin cross-linked demineralized bone matrices (HC-DBM) pre-loaded with vascular endothelial growth factor (VEGF) were designed to promote cells and new microvessels invasion into the matrices. After being chemical crosslinked with heparin by N-hydroxysuccinimide and N-(3-di-methylaminopropyl)-N'-ethylcarbodiimide, the scaffold could bind more VEGF than the non-crosslinked one and achieve localized and sustained delivery. The biological activity of VEGF binding on heparinized collagen was demonstrated by promoting endothelial cells proliferation. Evaluation of the angiogenic potential of heparinized DBM loaded with VEGF was further investigated by subcutaneous implantation. Improved angiogenesis of heparinized DBM loaded with VEGF was observed from haematoxylin-eosin staining and immunohistochemistry examination. The results demonstrated that heparin cross-linked DBM binding VEGF could be a useful strategy to stimulate cells and blood vessels invasion into the scaffolds.

Effects of alcohol and nicotine on the mechanical resistance of bone and bone neoformation around hydroxyapatite implants

The consumption of alcohol or nicotine is harmful to the integrity of bone tissue, hindering or even impeding the fixation and maintenance of bone implants. The aim of the present work was to evaluate the effects of ethanol and nicotine, when consumed alone and simultaneously, on both bone mechanical resistance and bone neoformation around hydroxyapatite implants. Twenty rats were divided into four groups: control (CT), alcohol (A), nicotine (N) and nicotine + alcohol (N + A). After 4 weeks of alcohol and/or nicotine consumption, dense (HAD) and porous (HAP) bodies were respectively implanted in a surgically produced bone defect in the right and left tibiae. After the surgeries, the animals continued to consume alcohol and/or nicotine. After ninety days, the animals were sacrificed and the tibiae and femurs were isolated for histological processing and mechanical assays. All the animals presented newly formed bone tissue close to the HAD and HAP ceramic bodies. The animals of the N + A group presented a smaller volume of neoformed bone. Group A animals presented smaller bone volume around the implants in relation to the animals from group N. Bone resistance to mechanical loads was smallest in animals from the N + A group, followed (in order) by the A and N groups. Thus, it can be concluded that nicotine or alcohol consumption produced negative effects on bone mechanical resistance and on the osteogenesis around the HAD and HAP implants. In addition, the simultaneous consumption of the two substances intensified their harmful effects.

Crosslinking heparin to collagen scaffolds for the delivery of human platelet-derived growth factor

Platelet-derived growth factor (PDGF) plays an important role in tissue regeneration and wound repair. However, the lack of effective delivery and the efficient targeting specificity limits its clinical applications. Here, heparin possessing PDGF binding domain was crosslinked to the collagen-based demineralized bone matrix (DBM) for the delivery of human PDGF(HC-PDGF). In in vitro experiments, heparin improves the binding of PDGF to collagen. In vitro activity assay indicates that collagen-heparin-PDGF (CH-PDGF) promotes human fibroblasts to proliferate on collagen gel. In addition, HC-PDGF stimulates cells to migrate into DBM scaffolds after implantation. The histological analysis shows that HC-PDGF promotes vascularization of the implants. In summary, heparin-DBM/PDGF could prevent the diffusion of PDGF, prolong its activity, and promote the cellularization and vascularization of the scaffold.

Tissue engineering for bone defect healing: an update on a multi-component approach

The need for an interdisciplinary approach in order to establish new therapeutic strategies for the therapy of bone defects has been acknowledged by the scientific community for many years. This awareness makes itself felt when looking at the multitude of approaches--ranging from cell-based to scaffold-based strategies and also including the use of osteogenic growth factors and genetic engineering--that are currently being combined to assess their potential to develop effective concepts for the treatment of extensive loss of osseous tissue. With a strong focus on the preclinical research in this field, the goal of this review is to give an update on the multi-component approaches that are currently being investigated in tissue engineering of bone.

Effects of Ethanol Consumption on Periodontal Inflammation in Rats

Studies suggest a correlation between ethanol consumption and periodontal disease. We hypothesized that elevated levels of blood reactive oxygen species following ethanol consumption may increase inflammation in periodontal tissue. Rats were divided into 4 groups (6–7 rats/group). Two groups were fed an ethanol-containing liquid diet, and 2 groups were fed a pair-fed control diet. In one of each dietary group, periodontitis was ligature-induced, while the other group was left unligated. Chronic ethanol feeding alone decreased the ratio of reduced/oxidized glutathione and increased 8-hydroxydeoxy-guanosine and tumor necrosis factor (TNF)-α levels in the gingiva. Blood hydroperoxides were also increased. In ligature-induced periodontitis lesions, ethanol feeding enhanced polymorpho-nuclear leukocyte infiltration and TNF-α expression. The results suggest that chronic alcohol consumption increased periodontal inflammation, oxidative damage, and TNF-α production and had an additive effect on polymorphonuclear leukocyte infiltration and gingival oxidative damage, increasing the severity of periodontal inflammation in the ligature model.

The effect of crosslinking heparin to demineralized bone matrix on mechanical strength and specific binding to human bone morphogenetic protein-2

Demineralized bone matrix (DBM) is a collagen-based scaffold, but its low mechanical strength and limited BMP-2 binding ability restrict its application in bone repair. It is known that heparin could be immobilized onto scaffolds to enhance their binding of growth factors with the heparin-binding domain. Here, we crosslinked heparin to DBM to increase its BMP-2 binding ability. To our surprise, the mechanical strength of DBM was also dramatically increased. The compression modulus of heparin crosslinked DBM (HC-DBM) have improved (seven-fold increased) under wet condition, which would allow the scaffolds to keep specific shapes in vivo. As expected, HC-DBM showed specific binding ability to BMP-2. Additional studies showed the bound BMP-2 exerted its function to induce cell differentiation on the scaffold. Subcutaneous implantation of HC-DBM carrying BMP-2 showed higher alkaline phosphatase (ALP) activity (2 weeks), more calcium deposition (4 and 8 weeks) and more bone formation than that of control groups. It is concluded that HC-DBM has increased mechanical intensity as well as specific BMP-2 binding ability; HC-DBM/BMP-2 enhances the osteogenesis and therefore could be an effective medical device for bone repair.

Effects of low-dose parathyroid hormone on bone mass, turnover, and ectopic osteoinduction in a rat model for chronic alcohol abuse

Parathyroid hormone (PTH) is used clinically in osteoporotic patients to increase bone mass by enhancing bone formation. PTH therapy is not uniformly effective at all skeletal sites and "life-style" factors may modulate the skeletal response to PTH. Alcohol may represent one of these factors. Chronic alcohol abuse is associated with osteoporosis and impaired fracture healing. Therefore, the present study investigated the effects of alcohol on the bone anabolic response to a dose of PTH similar to a human therapeutic dose 1) during normal cancellous and cortical bone growth and turnover, and 2) in a model of demineralized allogeneic bone matrix (DABM)-induced osteoinduction. Three-month-old male Sprague Dawley rats were fed a Lieber-DeCarli liquid diet with 35% of the calories derived from ethanol. The controls were pair-fed an alcohol-free isocaloric diet containing maltose-dextran. Following adaptation to the liquid diets, the rats were implanted subcutaneously with DABM cylinders prepared from cortical bone of rats fed normal chow. The rats were subsequently treated daily with PTH (1 microg/kg/d sc, 5 d/week) or vehicle and measurements on bone and DABM implants performed 6 weeks later. Total bone mass was evaluated on the day of necropsy using DXA. Tibiae were processed for histomorphometry. Bone mass and architecture in tibial diaphysis and DABM implants were evaluated by muCT. PTH treatment increased whole body bone mineral content (BMC) and bone mineral density (BMD). The hormone also increased bone formation and bone area/tissue area in the proximal tibial metaphysis. In contrast, PTH treatment had no effect on periosteal bone formation and minimal effects on DABM-induced osteoinduction. Alcohol consumption decreased whole body BMC. Alcohol also decreased cancellous as well as cortical bone formation and bone mass in tibia and impaired DABM-mediated osteoinduction. There was no interaction between PTH treatment and alcohol consumption for any of the endpoints evaluated. Our results indicate that the bone anabolic response to a therapeutic dose of PTH in the rat is largely confined to cancellous bone. In contrast, alcohol consumption inhibits bone formation at all sites. Furthermore, alcohol inhibits osteoinduction and reduces periosteal and cancellous bone formation, irrespective of therapeutic PTH administration. Based on the animal model, our findings suggest that alcohol consumption could impair the beneficial effects of PTH therapy in osteoporosis.