Skin diseases in laboratory mice: approaches to drug target identification and efficacy screening

Dermal toxicity studies: factors impacting study interpretation and outcome

The field of dermal toxicity continues to evolve in order to accurately predict dermal (and systemic) responses in humans to topically applied chemicals. Although the testing methods have undergone extensive refinements, idiosyncrasies and unexpected issues during the conduct of these studies are not unusual due to the plethora of new vehicles available for formulating test substances, changing regulatory requirements, and introducting new strain and/or species of laboratory animals as no single species or method seems to suffice for evaluating skin toxicity. The objective of this article is to illustrate some pragmatic issues that should be considered during the conduct as well as interpretation of dermal toxicity studies. Routine procedure-related issues such as hair clipping, tape stripping, and wrapping the animal's torso to prevent oral ingestion can influence the interpretation. Excipients used in dermal toxicity studies may be nontoxic when used alone but complex dermal formulations can result in unexpected irritation and toxicity. In conclusion, interpretation and risk assessment of dermal toxicity studies should be done in a comprehensive manner, taking into account procedure-related impact on study results, unique species susceptibility, limitation of gross visual (naked eye) observation for evidence of toxicity, and normal anatomical variation.

The emerging use of bone marrow-derived mesenchymal stem cells in the treatment of human chronic wounds

INTRODUCTION

Close to 5 million people in the USA are affected by chronic wounds, and billions of dollars are spent annually for their treatment. Despite advances in chronic wound management over the past decades, many patients afflicted with chronic wounds fail to heal or their ulcers recur. There is emerging evidence that the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) can offset this situation of impaired healing.

AREAS COVERED

This article provides a review of the use of BM-MSC for the treatment of chronic wounds, the current development of stem cell delivery to chronic wounds and related challenges are also described in this manuscript.

EXPERT OPINION

Numerous animal studies and a few pilot studies in human wounds have shown that BM-MSC can augment wound closure. Still, the primary contribution of mesenchymal stem cells (MSCs) to cutaneous regeneration and the long-term systemic effects of MSCs are yet to be established. In addition, we need to determine whether other types of stem/progenitor cells will be more effective. Therefore, more randomized controlled clinical trials need to be undertaken. It is of importance to remember that even with the most advanced and sophisticated therapeutic approaches, proper wound care and adherence to basic principles remain critical.