A Dermal Equivalent Engineered with TGF‐β3 Expressing Bone Marrow Stromal Cells and Amniotic Membrane: Cosmetic Healing of Full‐Thickness Skin Wounds in Rats

Abstract

Transforming growth factor beta-3 (TGF-β3) has been shown to decrease scar formation after scheduled topical applications to the cutaneous wounds. This study aimed to continuously deliver TGF-β3, during the early phase of wound healing, by engineering a dermal equivalent (DE) using TGF-β3 expressing bone marrow stromal cells (BM-SCs) and human dehydrated amniotic membrane (hDAM). To engineer a DE, rat BM-SCs were seeded on the hDAM and TGF-β3 was transiently transfected into the BM-SCs using a plasmid vector. Pieces of the dermal equivalent were transplanted onto the full-thickness excisional skin wounds in rats. The process of wound healing was assessed by image analysis, Manchester Scar Scale (MSS), and histopathological studies 7, 14, 21, and 85 days after the excision. The results confirmed accurate construction of recombinant pcDNA3.1-TGF-β3 expression system and showed that the transfected BM-SCs seeded on hDAM expressed TGF-β3 mRNA and protein from day 3 through day 7 after transfection. After implantation of the DE, contraction of the wounds was measured from day 7 through 21 and analyzed by linear regression, which revealed that the rate of wound contraction in all experimental groups was similar. Histologic evaluation demonstrated that transfected BM-SCs decreased retention and recruitment of the cells during the early stage of wound healing, decreased the formation of vascular structures and led to formation of uniformly parallel collagen bundles. MSS scores showed that TGF-β3 secreting cells significantly improved the cosmetic appearance of the healed skin and decreased the scar formation. From these results, it could be concluded that transient secretion of TGF-β3, during the early phase of healing, by BM-SCs seeded on hDAM can improve the cosmetic appearance of the scar in cutaneous wounds without negatively affecting the process of wound repair.

Immune Regulation of Skin Wound Healing: Mechanisms and Novel Therapeutic Targets

“…TGF-b3 significantly decreased scar size in both phase I and II clinical trials, though complete regeneration was never achieved and it failed to meet efficacy standards in phase III. 7,8 In the case of therapeutics for both chronic wounds and scar prevention, it is believed that improved delivery methods that permit sustained release may facilitate clinical effectiveness.…”

“…However, since temporal variation critically affects healing, continuing studies are exploring the efficacy of continuously delivering TGF-b3 in de- creasing scarring. 7 M6P is a potent inhibitor of TGF-b1 and TGF-b2. While it was successful in phase I clinical trials, in the phase II exploratory trial neither topical nor intradermal application showed statistical significance.…”

Functional Skin Grafts: Where Biomaterials Meet Stem Cells

“…AAMs preserve the tissue ECM properly and have a potential use as a membrane for skin wound healing. TGF- β 3 expressing bone marrow stromal cells cultured on AAM as a dermal equivalent led to the deposition of parallel, uniform collagen bundles with improved cosmetic appearance and decreased scar formation when transplanted onto full-thickness excisional skin wounds in rats for 85 days [129]. The decellularized matrix can serve as ready-to-use tissue models with essential ECM molecules like collagen, elastins, GAGs, and growth factors for improved cell attachment and proliferation.…”

Designer Exosomes: A New Platform for Biotechnology Therapeutics

“…Finally, using previously described parental cell-based and direct methods, therapeutic molecules including drugs, mRNAs, miRNAs, siRNAs, peptides, growth factors, anti-scarring factors (transforming growth factor [TGF]β1 inhibitors such as decorin and TGFβ3 [ 121 , 122 ]), and wound healing factors (SDF-1, which has a chemotactic function for bone marrow MSCs [BMSCs] and endothelial progenitor cells [EPCs] in vascularization and healing [ 123 ]) can be efficiently loaded (as fully described in Sect. 3.1) into the regenerative engineered exosomes.…”