The role of topical containing camellia sinensis in the cosmetic management of skin scars in healthy human volunteers: part 2
Epigallocatechin-3-gallate (EGCG), a polyphenol, influences cutaneous wound healing due to its anti-angiogenic, anti-inflammatory and anti-oxidant properties. We previously showed EGCG is effective in improving skin scarring when applied immediately post-injury. Here, this double-blinded randomized placebo-controlled trial compared the effects of pre-emptive priming versus immediate and delayed topical EGCG compared with placebo.  This was evaluated in 40 healthy human volunteers, over 8 weeks, in scars created in their upper inner arms using skin punch biopsies. Participants were split into 4 groups; each undergoing different modes of application versus placebo: Group 1=priming (7D) pre-injury, Group 2=priming (3D) pre-injury, Group 3=immediate (0D) day-of-injury, Group 4=delayed application (14D) post-injury. RNA sequencing was used here based on 72 samples: Group 1: day 0 (n=3 placebo, n=3 EGCG), week 4 (n=3 placebo, n=3 EGCG), week 8 (n=3 placebo, n=3 EGCG); Group 2: day 0 (n=3 placebo, n=3 EGCG), week 4 (n=3 placebo, n=3 EGCG), week 8 (n=3 placebo, n=3 EGCG), Group 3:  day 0 (n=6), week 4 (n=3 placebo, n=3 EGCG), week 8 (n=3 placebo, n=3 EGCG), Group 4: day 0 (n=6), week 4 (n=3 placebo, n=3 EGCG), week 8 (n=3 placebo, n=3 EGCG). The common differentially expressed genes identified between treated (EGCG) and placebo samples were grouped according to time point and group. Further exploration of these genes using Gene Ontology and Ingenuity Pathway Analysis revealed gene signatures of relevant biological processes and pathways. Here, RNA sequencing revealed a number of angiogenic, inflammatory genes that were significantly downregulated with EGCG particularly in pre-emptive priming Group 1 at week 4 including; hemoglobin subunit beta (HBB), hemoglobin subunit alpha-1 (HBA1) and hemoglobin subunit alpha-2 (HBA2) at week-4. Overall design: mRNA profiles of human skin scars over 8 weeks (treatment EGCG versus placebo) were generated by sequencing, in triplicate, using Illumina PE150 Platform.