Isotretinoin effect on the repair of bone defects – A study in rat calvaria

Effect of isotretinoin on induced tooth movement in rats

INTRODUCTION

This study was performed to evaluate the effect of isotretinoin on tooth displacement and tissues related to induced tooth movement (ITM) in rats.

METHODS

Wistar rats were randomly divided into 4 groups: vegetable oil (O; n = 40), 7.5 mg/kg isotretinoin (I; n = 40), vegetable oil + ITM (OM; n = 44), and 7.5 mg/kg isotretinoin and ITM (IM; n = 39). After the daily application of the solutions for 30 days, an orthodontic appliance was installed to mesially displace the maxillary first right molar (30 cN) of rats in the OM and IM groups. The animals were killed 2, 7, 14, or 21 days after placement of the devices. The animals in the O and I groups did not undergo ITM but were killed simultaneously. The animals were examined for tooth displacement, the neoformation of mature collagen, bone and root resorption, the presence of hyalinized areas, and trabecular bone modeling by microcomputed tomography.

RESULTS

There was no difference in tooth displacement, the number of osteoclasts, the presence of hyalinized areas, or trabecular bone among the O, I, OM, and IM groups across the periods tested (P >0.05). A lower percentage of mature collagen was found in the IM group than in the OM group on day 7 (P <0.05). A lower frequency of root resorption was found in the IM group than in the OM group on days 2 and 21 (P <0.05).

CONCLUSIONS

Isotretinoin at 7.5 mg/kg decreased root resorption in rats subjected to ITM.

Effects of isotretinoin on new bone formation after maxillary sutural expansion

PURPOSE

The aim of this study was to examine the effects of isotretinoin on new bone formation after maxillary sutural expansion in rats.

MATERIALS AND METHODS

A total of 32 male Wistar rats were selected and randomly divided into four groups. The isotretinoin group was treated with 7.5 mg/kg isotretinoin, and the soybean group was treated with 2 ml/kg soybean oil for 57 days. The substances were applied via oral gavage. The expansion-only and the control groups were not treated with any substance. In the experiment groups, expansion springs were applied on day 41 of the experiment, and after day 5 of expansion, a 12-day retention period was established. At the end of the experiment, all the animals were sacrificed, and their maxillae were dissected for histological evaluation. The numbers of osteoclasts, osteoblasts and formation of new bone and capillaries were evaluated on slides centered around the suture.

RESULTS

The statistical analysis showed significant differences between the groups for the number of osteoblasts and osteoclasts (p < 0.001). In the experiment groups, higher numbers of osteoblasts and osteoclasts were detected in comparison to the control group (p < 0.001), while there was no significant difference between the experiment groups. Capillary formation and new bone formation in the isotretinoin group were found to be on a higher level than in the other groups (p < 0.001).

CONCLUSION

Isotretinoin had no negative effects on bone formation following the expansion of the maxillary suture in rats.

The safety of isotretinoin treatment in patients with bone fractures

Isotretinoin is widely applicable in dermatology, although it may develop severe side effects in the skeletal system. An intention of this review was to establish the safety of oral isotretinoin in patients with bone fractures. Both MEDLINE/Pubmed and SCOPUS databases were searched to investigate the influence of isotretinoin on the skeletal system. The drug shows a strong osteoporotic activity in rats whereas this effect is milder in humans. Biochemical markers of bone turnover remain unchanged except for serum calcium in patients receiving a high dose of isotretinoin. An excessive intake of vitamin A may impair functioning of vitamin D especially in people with a vitamin D deficiency, therefore a similar side effect may also occur in patients on isotretinoin treatment. We suggest reducing the use of isotretinoin after bone injury or continuing the treatment at low dosing with a concomitant correction of vitamin D and calcium status.

Preclinical therapies to prevent or treat fracture non-union: A systematic review

Background

Non-union affects up to 10% of fractures and is associated with substantial morbidity. There is currently no single effective therapy for the treatment or prevention of non-union. Potential treatments are currently selected for clinical trials based on results from limited animal studies, with no attempt to compare results between therapies to determine which have the greatest potential to treat non-union.

Aim

The aim of this systematic review was to define the range of therapies under investigation at the preclinical stage for the prevention or treatment of fracture non-union. Additionally, through meta-analysis, it aimed to identify the most promising therapies for progression to clinical investigation.

Methods

MEDLINE and Embase were searched from 1^St January 2004 to 10^th April 2017 for controlled trials evaluating an intervention to prevent or treat fracture non-union. Data regarding the model used, study intervention and outcome measures were extracted, and risk of bias assessed.

Results

Of 5,171 records identified, 197 papers describing 204 therapies were included. Of these, the majority were only evaluated once (179/204, 88%), with chitosan tested most commonly (6/204, 3%). Substantial variation existed in model design, length of survival and duration of treatment, with results poorly reported. These factors, as well as a lack of consistently used objective outcome measures, precluded meta-analysis.

Conclusion

This review highlights the variability and poor methodological reporting of current non-union research. The authors call for a consensus on the standardisation of animal models investigating non-union, and suggest journals apply stringent criteria when considering animal work for publication.

Is It Safe to Operate on Patients Taking Isotretinoin?

BACKGROUND

Oral isotretinoin is increasingly being used to treat acne and other dermatological conditions. The number of patients who take isotretinoin and wish or need to undergo plastic surgery may be following a similar pattern. Although skin healing is an important concern in the case of patients who use isotretinoin, it is definitely not the only relevant issue when planning surgical intervention.

METHODS

Eleven important points regarding surgery safety in patients taking oral isotretinoin were defined. A literature search of the PubMed database was conducted by employing the keywords isotretinoin OR 13-cis-retinoic acid. This returned the largest possible number of studies about isotretinoin.

RESULTS

Forty-seven studies matched the selection criteria. Most animal experimental models suggested that isotretinoin at doses commonly used to treat acne is not detrimental to wound healing. Human studies are controversial. However, healing of skeletal muscle could be at increased risk of necrosis.

CONCLUSIONS

Association between isotretinoin and problematic skin healing after surgery is being challenged. Also, recommended time between discontinuation of isotretinoin and surgery should be reviewed. While muscle flaps may be endangered in patients taking isotretinoin, healing of other tissues and systemic effects that could compromise surgery safety are rare or detectable before surgery.

LEVEL OF EVIDENCE V

This journal requires that the authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Hydrogels functionalized with N-cadherin mimetic peptide enhance osteogenesis of hMSCs by emulating the osteogenic niche

N-cadherin is considered to be the key factor in directing cell-cell interactions during mesenchymal condensation, which is essential to osteogenesis. In this study, hyaluronic acid (HA) hydrogels are biofunctionalized with an N-cadherin mimetic peptide to mimic the pro-osteogenic niche in the endosteal space to promote the osteogenesis of human mesenchymal stem cells (hMSCs). Results show that the conjugation of the N-cadherin peptide in the HA hydrogels enhances the expression of the osteogenic marker genes in the seeded hMSCs. Furthermore, the biofunctionalized HA hydrogels promote the alkaline phosphatase activity, type I collagen deposition, and matrix mineralization by the seeded hMSCs under both in vitro and in vivo condition. We postulate that the biofunctionalized hydrogels emulates the N-cadherin-mediated homotypic cell-cell adhesion among MSCs and the "orthotypic" interaction between the osteoblasts and MSCs. These findings demonstrate that the biofunctionalized HA hydrogels provide a supportive niche microenvironment for the osteogenesis of hMSCs.