Influence of low-dose nicotine on bone healing

How Do Drugs Affect the Skeleton? Implications for Forensic Anthropology

Simple Summary

Forensic anthropologists analyze human remains to assist in the identification of the deceased, predominantly by assessing age-at-death, sex, stature, ancestry and any unique identifying features. Whilst methods have been established to create this biological profile of the skeleton, these may be influenced by a number of factors. This paper, for the first time, provides an overview from a reading of the clinical and pharmacological literature to explore whether the intake of drugs can affect the skeleton and whether these may have implications for forensic anthropology casework. In effect, drugs such as tobacco, heroin, and prescription medications can alter bone mineral density, can increase the risk of fractures, destroy bone and changes to the dentition. By considering how drugs can affect the skeleton, forensic anthropologists can be aware of this when attempting to identify the deceased.

Abstract

Forensic anthropologists rely on a number of parameters when analyzing human skeletal remains to assist in the identification of the deceased, predominantly age-at-death, sex, stature, ancestry or population affinity, and any unique identifying features. During the examination of human remains, it is important to be aware that the skeletal features considered when applying anthropological methods may be influenced and modified by a number of factors, and particular to this article, prescription drugs (including medical and non-medical use) and other commonly used drugs. In view of this, this paper aims to review the medical, clinical and pharmacological literature to enable an assessment of those drug groups that as side effects have the potential to have an adverse effect on the skeleton, and explore whether or not they can influence the estimation of age-at-death, sex and other indicators of the biological profile. Moreover, it may be that the observation of certain alterations or inconsistencies in the skeleton may relate to the use of drugs or medication, and this in turn may help narrow down the list of missing persons to which a set of human remains could belong. The information gathered from the clinical and medical literature has been extracted with a forensic anthropological perspective and provides an awareness on how several drugs, such as opioids, cocaine, corticosteroids, non-steroidal anti-inflammatory drugs, alcohol, tobacco and others have notable effects on bone. Through different mechanisms, drugs can alter bone mineral density, causing osteopenia, osteoporosis, increase the risk of fractures, osteonecrosis, and oral changes. Not much has been written on the influence of drugs on the skeleton from the forensic anthropological practitioner perspective; and this review, in spite of its limitations and the requirement of further research, aims to investigate the current knowledge of the possible effects of both prescription and recreational drugs on bones, contributing to providing a better awareness in forensic anthropological practice and assisting in the identification process of the deceased.

Mandatory Nicotine Cessation for Elective Orthopedic Hip Procedures Results in Reduction in Postoperative Nicotine Use

Purpose

To determine the efficacy of mandatory preoperative nicotine cessation on postoperative nicotine use, and to identify independent predictors of nicotine use relapse in subjects undergoing hip preservation surgery or total hip arthroplasty by a single fellowship-trained orthopedic surgeon.

Methods

Consecutive subjects that underwent hip surgery from November 2014 to December 2017 were reviewed. Subjects who self-reported nicotine use, quit prior to surgery, and completed a minimum one-year follow-up were included. Multiple linear regression models were constructed to determine the effect of independent variables on nicotine use relapse following surgery.

Results

Sixty subjects were included in the study (mean follow-up 35.1 months (17-57 months), mean age 44.9 years (20-82 years), and 23 (38.3%) males). Twenty-eight subjects (46.7%) remained nicotine-free at final follow-up. The mean number of cigarettes per day decreased from 13.4 preoperatively to 8.4 postoperatively in the subjects who relapsed (P=0.002). The mean time to return to nicotine postoperatively was 2.4 months. The number of preoperative cigarettes per day was the only independent predictor of tobacco use relapse (P=0.005).

Conclusion

Mandatory preoperative nicotine cessation prior to elective hip surgery demonstrates a 46.7% nicotine-free survivorship at final follow-up with the number of preoperative cigarettes per day found to be the only independent predictor of nicotine use relapse.

Level of evidence

The level of evidence of this research study is Level III since it is a non-experimental study with a cohort of patients.

Histopathologic and Immunohistochemical Investigation of the Effects of Vitamin C on Bone Healing in Rats Exposed to Nicotine

PURPOSE

The aim of the present study was to perform a histopathologic and immunohistochemical investigation of the effects of vitamin C on bone healing in rats exposed to nicotine.

MATERIALS AND METHODS

A total of 52 male Sprague-Dawley rats were assigned to 4 main groups: control, vitamin C, nicotine, and nicotine plus vitamin C. The rats in the nicotine groups were injected with nicotine at 12-hour intervals for 4 weeks. At the end of 4 weeks, a tibial defect was created in all the rats. Subcutaneous injections were administered at the same intervals postoperatively, and the vitamin C groups received intraperitoneal vitamin C injections every day for the first 3 days and then every other day postoperatively. The rats were sacrificed on postoperative days 7 and 21. The blood samples collected during sacrifice were tested to determine the blood cotinine levels, and histopathological and immunohistochemical analyses were performed on tibia samples.

RESULTS

The histopathologic evaluation revealed that nicotine significantly increased the amount of necrosis and significantly decreased new bone formation and the bone healing score. The presence of necrosis in the nicotine plus vitamin C group was significantly lower on day 21 (P = .005). A statistically significant difference was observed among the new bone formation of the control, nicotine, vitamin C, and nicotine plus vitamin C groups on day 21 (P = .001). The new bone healing score of the nicotine group was significantly lower than that of the control, vitamin C, and nicotine plus vitamin C groups (P = .003, P = .001, and P = .001). The immunohistochemical evaluation showed that nicotine increased the hypoxia-inducible factor-1α and vascular endothelial growth factor levels and decreased the bone morphogenetic protein-2 levels, especially in the groups sacrificed on day 21.

CONCLUSIONS

Vitamin C did not have a significant effect on bone healing. However, vitamin C administered with nicotine decreased the metabolism of nicotine and, thus, increased nicotine excretion.

Effect of serum nicotine level on posterior spinal fusion in an in vivo rabbit model

BACKGROUND CONTEXT

Cigarette smoking has a deleterious effect on spinal fusion. Although some studies have implied that nicotine is primarily responsible for poor fusion outcomes, other studies suggest that nicotine may actually stimulate bone growth. Hence, there may be a dose-dependent effect of nicotine on posterior spinal fusion outcomes.

PURPOSE

The purpose of this study was to determine if such a relationship could be shown in an in vivo rabbit model.

STUDY DESIGN/SETTING

This is a prospective in vivo animal study.

METHODS

Twenty-four adult male New Zealand white rabbits were randomly divided into four groups. All groups received a single-level posterolateral, intertransverse process fusion at L5-L6 with autologous iliac crest bone. One group served as controls and only underwent the spine fusion surgery. Three groups received 5.25-, 10.5-, and 21-mg nicotine patches, respectively, for 5 weeks. Serum nicotine levels were recorded for each group. All animals were euthanized 5 weeks postoperatively, and spinal fusions were evaluated radiographically, by manual palpation, and biomechanically. Statistical analysis evaluated the dose response effect of outcomes variables and nicotine dosage. This study was supported by a portion of a $100,000 grant from the Orthopaedic Research and Education Foundation. Author financial disclosures were completed in accordance with the journal's guidelines; there were no conflicts of interests disclosed that would have led to bias in this work.

RESULTS

The average serum levels of nicotine from the different patches were 7.8±1.9 ng/mL for the 5.25-mg patch group; 99.7±17.7 ng/mL for the 10.5-mg patch group; and 149.1±24.6 ng/mL for the 21-mg patch group. The doses positively correlated with serum concentrations of nicotine (correlation coefficient=0.8410, p<.001). The 5.25-mg group provided the best fusion rate, trabeculation, and stiffness. On the basis of the palpation tests, the fusion rates were control (50%), 5.25 mg (80%), 10.5 mg (50%), and 21 mg (42.8%). Radiographic assessment of trabeculation and bone incorporation and biomechanical analysis of bending stiffness ratio were also greatest in the 5.25-mg group. Radiographic evaluation showed a significant (p=.0446) quadratic effect of nicotine dose on spinal fusion.

CONCLUSIONS

The effects of nicotine on spinal fusion are complex, may be dose dependent, and may not always be detrimental. The uniformly negative effects of smoking reported in patients undergoing spinal fusion may possibly be attributed to the other components of cigarette smoke.

The convergence of fracture repair and stem cells: interplay of genes, aging, environmental factors and disease

The complexity of fracture repair makes it an ideal process for studying the interplay between the molecular, cellular, tissue, and organ level events involved in tissue regeneration. Additionally, as fracture repair recapitulates many of the processes that occur during embryonic development, investigations of fracture repair provide insights regarding skeletal embryogenesis. Specifically, inflammation, signaling, gene expression, cellular proliferation and differentiation, osteogenesis, chondrogenesis, angiogenesis, and remodeling represent the complex array of interdependent biological events that occur during fracture repair. Here we review studies of bone regeneration in genetically modified mouse models, during aging, following environmental exposure, and in the setting of disease that provide insights regarding the role of multipotent cells and their regulation during fracture repair. Complementary animal models and ongoing scientific discoveries define an increasing number of molecular and cellular targets to reduce the morbidity and complications associated with fracture repair. Last, some new and exciting areas of stem cell research such as the contribution of mitochondria function, limb regeneration signaling, and microRNA (miRNA) posttranscriptional regulation are all likely to further contribute to our understanding of fracture repair as an active branch of regenerative medicine.

The in vitro and in vivo effects of nicotine on bone, bone cells and fracture repair

INTRODUCTION

Cigarette smoke has negative effects on bone metabolism and fracture repair. However, no study has reviewed effects of nicotine on bone and fracture repair independent of other constituents of cigarette smoke. The authors review the existing evidence of the effect of nicotine on 'bone' and 'bone cells' and fracture repair, drawing conclusions relevant to clinical practice and future research.

AREAS COVERED

A literature review was conducted using PRISMA guidelines and PubMed, Cochrane, MEDLINE/OVID, EMBASE, NHS Evidence and Google scholar databases. Articles were included if they specifically investigated the effects of nicotine on 'bone' or fracture repair in animal or human models or in vitro effects on 'bone cells'. A total of 64 papers were included in this review, of which 15 were human in vitro studies and 49 animal studies wherein 9 were in vitro and 40 in vivo. In vivo studies of the effects of nicotine in animals demonstrated widespread effects on bone including osteoneogenesis, osseointegration, steady-state skeletal bone and genes and cytokines relevant to bone cell physiology and bone homeostasis. In these studies, nicotine's effects are predominately negative, inhibiting bone cell metabolism and fracture repair, whereas most in vitro studies reported biphasic responses in all bone cells except osteoclastic cells.

EXPERT OPINION

The review suggests that nicotine has effects on osteoneogenesis, osseointegration and steady-state skeletal bone in animal in vivo models, as well as effects on all 'bone cells', via several mechanisms in both animal and human cell in vitro studies. The effect of nicotine is dose-dependent, with higher concentrations having predominantly negative effects, whereas at low concentrations a stimulatory effect is seen. Stimulatory effects on certain cells may indicate a possible, limited therapeutic role; advice regarding smoking cessation perioperatively should remain due to the other harmful components of cigarette smoke, but there may be scope for allowing the use of nicotine patches instead of complete abstention. Further research into clinical outcomes is required before the exact response of bone and fracture repair in humans to nicotine is known.

Peroxisome proliferator-activated receptor delta agonist attenuates nicotine suppression effect on human mesenchymal stem cell-derived osteogenesis and involves increased expression of heme oxygenase-1

Smoking has long been associated with osteoporosis, decreased bone mineral density, increased risk of bone fracture, and increased health costs. Nicotine, the main component of cigarette smoke, has major negative effects on bone metabolism and skeletal remodeling in vivo. Although osteoblasts and osteoblast-like cells have been used extensively to study the impact of nicotine, few studies have been performed on human mesenchymal stem cells (hMSCs). In this context, we examined the impact of nicotine on (a) hMSCs proliferation, (b) osteoblastic differentiation, (c) alkaline phosphatase (ALP) activity, and (d) expression of canonical genes during differentiation of hMSCs. MSCs isolated from human bone marrow were treated with different concentrations (0, 0.1, 1 and 10 μM) of nicotine for 7 days. Nicotine caused a dose-dependent decrease in cell proliferation, decreased heme oxygenase-1 (HO-1) expression (p < 0.05) and attenuated osteogenesis (p < 0.05) in hMSCs (45 % reduction at day 14). In addition, nicotine caused a dose-dependent decrease in alizarin red staining for calcium and staining for ALP. Induction of HO-1 by peroxisome proliferator-activated receptor delta agonist (GW0742) prevented the effect of nicotine. Nicotine caused a dose-dependent reduction in the expression of BMP-2, a well-known marker for bone formation; however, this was prevented by GW0742 treatment. Therefore, induction of HO-1 prevents the deleterious effects of nicotine on osteogenesis in hMSC. This offers insight into both how nicotine affects bone remodeling and a therapeutic approach to prevent fracture and osteoporosis in smokers.

Smoking affects mRNA expression of bone morphogenetic proteins in human periosteum

Periosteum is important for bone homoeostasis through the release of bone morphogenetic proteins (BMPs) and their effect on osteoprogenitor cells. Smoking has an adverse effect on fracture healing and bone regeneration. The aim of this study was to evaluate the effect of smoking on the expression of the BMPs of human periosteum. Real-time polymerase chain reaction was performed for BMP-2,-4,-6,-7 gene expression in periosteal samples obtained from 45 fractured bones (19 smokers, 26 non-smokers) and 60 non-fractured bones (21 smokers, 39 non-smokers). A hierarchical model of BMP gene expression (BMP-2 > BMP-6 > BMP-4 > BMP-7) was demonstrated in all samples. When smokers and non-smokers were compared, a remarkable reduction in the gene expression of BMP-2, -4 and -6 was noticed in smokers. The comparison of fracture and non-fracture groups demonstrated a higher gene expression of BMP-2, -4 and -7 in the non-fracture samples. Within the subgroups (fracture and non-fracture), BMP gene expression in smokers was either lower but without statistical significance in the majority of BMPs, or similar to that in non-smokers with regard to BMP-4 in fracture and BMP-7 in non-fracture samples. In smokers, BMP gene expression of human periosteum was reduced, demonstrating the effect of smoking at the molecular level by reduction of mRNA transcription of periosteal BMPs. Among the BMPs studied, BMP-2 gene expression was significantly higher, highlighting its role in bone homoeostasis.

Nicotine-induced chondrogenic differentiation of human bone marrow stromal cells in vitro

PURPOSE

Nicotine has been reported that it has a dose-dependent effect on matrix mineralization by human bone marrow cells. However, there is no relevant research concerning on chondrogenic differentiation potential of bone marrow stromal stem cells (BMSCs) treated with nicotine in vitro. The aims of the study were to examine the effects of nicotine (0, 10(-7), 10(-6) and 10(-5) M) on the proliferation and chondrogenic differentiation of BMSCs from three healthy donors in vitro.

METHODS

BMSCs proliferation was analyzed by CCK8 assay and real-time polymerase chain reaction was used to assay the expression of type II collagen, aggrecan, type I collagen and type X collagen. The proteoglycan content was stained by Alcian blue, and the sulfated glycosaminoglycan (sGAG) content of BMSCs was quantified spectrofluorometrically using dimethylmethylene blue.

RESULTS

The cell viability was not significantly impaired until up to a concentration of 10(-5) M nicotine. Nicotine promoted the proliferation and enhanced the expression of type II collagen at the level up to 10(-6) M (P < 0.05). The expression of aggrecan was reduced at the concentration of 10(-5) M nicotine at day 14 (P < 0.05), and there was no significant difference in aggrecan gene expression at 10(-7) and 10(-6) M nicotine levels compared to control group (n.s.). Also the fibroblastic and hypertrophic gene expressions were down-regulated in the chondrogenic medium with 10(-7)-10(-5) M nicotine (P < 0.05).

CONCLUSION

It was implied that local application of nicotine at an appropriate concentration may be a promising approach for enhancing chondrogenic differentiation capacity of BMSCs in cell-based cartilage tissue engineering. Also these results indicate that nicotine maybe a potentially useful drug for the treatment of Osteoarthritis.

Increased revision rates after total knee arthroplasty in patients who smoke

The purpose of this study was to compare the clinical outcomes of total knee arthroplasty in patients who reported a history of tobacco use with those who were nonsmokers. Between 2006 and 2009, there were 131 total knee arthroplasties performed in patients who were smokers and 490 in patients who did not smoke. At a mean follow-up of 47 months (range, 24-79 months), the patients who were smokers had a statistically decreased overall survivorship of 90% (13 revisions) compared with 99% (5 revisions) in the nonsmokers. Surgical complication rates were not significantly different between the 2 groups; however, there was a significant difference in medical complications. Total knee arthroplasty in smokers has a higher risk of negative clinical outcomes compared with nonsmokers.

The effect of nicotine on the mechanical properties of mesenchymal stem cells

PURPOSE: To measure the elasticity of the nucleus and cytoplasm of human mesenchymal stem cells (MSCs) as well as changes brought about by exposure to nicotine in vitro. METHODS: MSCs were synchronized to the G(0) stage of the cell cycle through serum deprivation techniques. The cells were then treated with medium containing nicotine (0.1 µM, 0.5 µM, and 1 µM). Atomic force microscopy was then used to measure the Young's modulus of both the nucleus and cytoplasm of these cells. RESULTS: For both unsynchronized and synchronized cells, the nucleus was softer than the cytoplasm, although this difference was not found to be statistically significant. The nucleus of cells treated with nicotine was significantly stiffer than the control for all concentrations. The cytoplasm was significantly stiffer in nicotine-treated cells than in control cells for the 0.5 µM and 1.0 µM concentrations only. CONCLUSIONS: The results of this study could suggest that nicotine affects the biophysical properties of human MSCs in a dose-dependent manner, which may render the cells less responsive to mechanoinduction and other physical stimuli.

Influence of nicotine on the biological activity of rabbit osteoblasts

OBJECTIVES

To assess the influence of nicotine on the proliferation and gene expression of osteogenic and angiogenic mediators of osteoblasts.

MATERIAL AND METHODS

Rabbit primary osteoblasts were exposed to various concentrations of nicotine (0.001, 0.1 and 10 μmol/l). The cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The gene expression of transforming growth factor (TGF)-β(1), bone morphogenetic protein (BMP)-2, platelet-derived growth factor (PDGF)-AA and vascular endothelial growth factor (VEGF) was evaluated using real-time reverse transcription - polymerase chain reaction.

RESULTS

The osteoblast proliferation was inhibited by nicotine at the concentration of 0.001-10 μM at 48 and 72 h of culture, but with no significant effect at 24 h. The expression of TGF-β(1), BMP-2, PDGF-AA and VEGF was inhibited by nicotine at the concentrations of 0.1 and 10 μM, but with no significant difference at the low concentration of 0.001 μM.

CONCLUSIONS

Nicotine suppresses osteoblast proliferation and inhibits the expression of some key osteogenic and angiogenic mediators in the in vitro experimental model. These inhibitory effects of nicotine on the osteoblast activity may reflect, to a certain degree, the overall detrimental effects of tobacco use on the survival rate of dental implants.