Gene Expression Studies Pertaining to Extracellular Matrix Integrity and Remodeling: Nuances and Pitfalls of In Vitro Investigations

December 2019 | Volume 18 | Issue 12 | Original Article | 1255 | Copyright © December 2019

Alan D. Widgerow MBBCh MMed (Plast) FCS FACS,a John A. Garruto BSb

aCenter for Tissue Engineering, Department of Plastic Surgery, University of California, Irvine, CA; Alastin Skincare Inc., Carlsbad CA
bFree Radical Technology, Inc, Oceanside, CA

Abstract
Anti-aging strategies using topicals with active agents demand validation and proof of efficacy. One investigation in this realm involves gene expression testing. This study undertakes gene expression analysis of Alastin Skincare Regenerating Skin Nectar (RSN) using an in vitro human skin model. The current study is similar to other published human skin model studies, but with additional time periods beyond 24-hours (which are more appropriate for testing peptides) and a suitable control for the Alastin non-aqueous product. Results show the Alastin product upregulates a large array of genes within areas of skin renewal, extracellular matrix remodeling, barrier function, and inflammation after 72 hours. The study provides gene expression data that support the clinical success of the product. It also demonstrates the difficulty and vulnerabilities in assessing efficacies of products with certain in vitro investigations when the nuances of that product are not considered.

J Drugs Dermatol. 2019;18(12):1255-1259.

INTRODUCTION

Skin renewal and regeneration are paramount to efforts in anti-aging strategies and rejuvenation. This is particularly relevant in a milieu of extracellular matrix (ECM) distortion and disruption brought about by extrinsic (photodamage) and intrinsic (aging) factors that initiate and maintain these changes.1,2 In an effort to counteract changes within the ECM and epidermis, peptides, growth factors, and other active ingredients have been used. In particular, a new generation of peptides has provided solutions to many challenges presented by biologic materials such as growth factors. Peptides’ very low molecular weights ensure absorption, synthetic manufacturing processes generate a predictable quality and quantity of stable actives, far lower amounts of potentially cytotoxic preservatives are needed for shelf life maintenance, and peptides have an increased safety profile related to unexpected cellular proliferation.3

When comparing efficacies of growth factors versus peptides, certain functional nuances need to be borne in mind when testing gene responses, particularly in laboratory environments. In that context, a recent study4 attempted to compare various formulations including growth factor- and non-growth factor-based skin care products, assessing their biologic activity based on gene expression responses.

Major limitations were identified related to this study, which included the following:
  • A single test period was examined (24 hours), which, while this time frame may be suited to growth factor stimulation, peptides behave differently and have been demonstrated in many cases to have maximal activity in gene expression at 48, 72, and even longer time periods.
  • When selecting controls, water may be ideal for certain aqueous formulations but for non-aqueous anhydrous preparations such as (Alastin Regenerating Skin Nectar), this provides potential inaccuracies.
  • Finally, although the skin culture EFT model selected has been successfully used as a surrogate for human studies, there are inherent limitations to testing combined cell lines. Although transcription (cell commands) signaling may be demonstrated, the true proof of efficacy often resides in the translational capacity of the product, that relating to new cell and protein regeneration. This is best represented by histological assess- ments of biopsies which take into account the ability of the actives to penetrate skin in a real world environment.

In an effort to address some of the limitations addressed above, a study was designed to test Alastin Skincare Regenerating Skin Nectar, ensuring analysis at two time points, selecting appropriate baseline control comparators, and using a broad panel of genes (Genemarkers Standard Skin Panel) covering a range of important biological functions in skin rather than a few selected genes.