Two dermatological concerns frequently received by esthetic practitioners are clinical manifestations of aging skin and androgenic alopecia (AGA). Signs of epithelial aging become evident as life progresses, resulting from both intrinsic (gene mutations, hormones, metabolism) and extrinsic (pollutants, UV light, and ionizing radiation) affronts [1]. Exogenously, photoaging and other environmental factors lead to alterations in pigment, loss of elasticity, fine lines and wrinkles, loss of hydration, telangiectasias, and increased risk of skin cancer [2]. Endogenously aged skin results in the atrophy of collagen and elastic extracellular matrices resulting in epidermal thinning and flattening of the dermo-epidermal junction [1]. Similar endogenic and exogenic abuses influence the cycle of hair growth and regeneration (anagen, catagen, and telogen phases) over time by reducing stem cell activity in the bulge of dermal papilla hair follicles [3]. While many patients seek treatment for concerns regarding facial and bodily regions, few desire traditional surgical intervention because of the associated risks and recovery time.

Recently stem cells, particularly easily obtained adipose-derived stem cells (ADSCs), have garnered popularity for their role in tissue maintenance and repair. ADSCs are effortlessly isolated following liposuction; lipoaspirate is obtained from clinics and centrifuged to obtain a stromal vascular fraction (SVF) which contains ADSCs, pericytes, hematopoietic progenitors, fibroblasts, endothelial cells, smooth muscle cells, monocytes, macrophages and lymphocytes [4]. Although other techniques could be performed to elute subsets of ADSCs, SVF was often used in whole to conserve time, cost, and labor and to obtain a 361 designation by the FDA. The 361 registration is for homologous-use tissue, which refers to the repair, reconstruction, replacement, or supplementation of a recipient’s cells that perform the same primary function in the recipient as in the donor. These products must be minimally manipulated, not combined with other agents, and collected and delivered in the same surgical setting. 361 contrasts with the 351-drug pathway for cellular or tissue products that do not meet the description of minimal manipulation. These products are typically cultured in a laboratory and processed in a way that alters their original form. Unlike the 361 registration, these products are required by the FDA to apply for an investigational new drug (IND), which can be costly and time-consuming. Unfortunately, companies have been marketing stem cells (SC) and exosome products without approval by the FDA, and a company’s stem cell (SC) product was found to contain no living SCs but did contain Escherichia coli bacteria causing sepsis in more than a dozen patients. After similar issues from various companies, the FDA issued a warning in December 2019, alerting the public to be cautious of any claims because there are no FDA- approved SC or exosome products, even under the 351-drug pathway. While many groups are pursuing cellular-based therapies for skin rejuvenation under 351 INDs, it is believed that many of the positive effects of ADSCs come from paracrine signaling derived from secreted exosomes and not directly from the cells themselves; thus, the use of a synthetically produced, acellular product has the benefit of bypassing current FDA regulations and can be immediately commercialized.

Skin Rejuvenation

Traditional non-excisional skin tightening methods have included topicals containing growth factors and cytokines (TGF-β, PDGF, FGF, IL-1, TNF-α, and retinoids) [5-11], dermal fillers (collagen, hyaluronic acid, hydroxyapatite, and Poly-L-lactic acid) [12-14], absorbable sutures (polydioxanone (PDO) threading) [15, 16], energy-/mechanical-based devices (microdermabrasion, moderate to deep chemical peels, fractional radiofrequency micro-needling, and fractional non-ablative and ablative lasers) [17-20]. While observable success has been achieved via conventional methods, they are not without their limitations. For example, growth factors and cytokines are large hydrophilic molecules with a >15,000 Da molecular weight, and prior studies demonstrate that hydrophilic molecules >500 Da have low penetration past the stratum corneum, questioning the efficacy of topicals [21]. Dermal fillers can create issues when collagen overstimulation leads to fibrosis, creating a stiff feeling, the inability to achieve a natural expression, and chronic swelling at the treatment area years after the initial injection. Benefits from PDO threading decline sharply after 12 weeks [16], and while some devices have proved their value over time, most are no longer currently in use. Minimally invasive subdermal RF treatments are currently the gold standard for significant skin tightening [22]. 

Recently the addition of biologicals (ADSCs, nano fat, and exosomes) to traditional procedures has gained traction with favorable outcomes. Multiple studies performed since 2001 have shown that ADSCs can improve collagen and elastin content in the skin and adipose framework [23]; however, the FDA’s disapproval of ‘more than minimal manipulation’ of autologous tissue led to a ban on the use of SVF techniques for stem cell treatments (http://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/framework-regulation-regenerative-medicine-products). This has led to increased interest in the use of extracellular vesicles (EVs), cell-derived, membranous structures released by nearly all human cells. Exosomes are 20-200nm acellular bilamellar EVs that contain miRNA, mRNA, and peptides which play essential roles in biological signaling, including skin homeostasis. The production of exosomes in a laboratory involves the use of conditioned media (CM) from cellular cultures, usually mesenchymal stem cells (MSCs). Exosomes have been shown to play a significant role in paracrine signaling, and their downstream purpose can vary significantly based on the composition of the cargo provided by the parent cell [24, 25]. It has been noted that paracrine signaling can generate up to 91% of the effects of injected stem cells [26] and thus is viewed as a promising new, “cell-free” therapy, safe from the undesired complications of traditional stem cell therapy such as tumorigenicity and immune rejection [27]. 

Microneedling is a procedure that punctures the skin at a controlled depth, causing an intrinsic wound-healing cascade promoting collagen formation and neovascularization. Migration and proliferation of fibroblasts also occur, resulting in the formation of intercellular matrix and deposition of collagen. Skin tightening and collagen formation continue for 5 to 7 years post-procedure [28]. The addition of platelet-rich plasma (PRP), growth factors, and conditioned media is being explored to decrease recovery time by downregulating inflammation and increasing textural improvement by continuing stimulation of collagen synthesis initiated by micro-needling. While the FDA has advised that micro-needling plus biological agents should be regulated as a drug, the agency is not enforcing the ruling at this time (https://www.fda.gov/regulatory-information/search-fda-guidance-documents/regulatory-considerations-microneedling-devices). Many groups have had significant success with controlled trials where RF micro-needling or CO2 laser resurfacing is performed with half the face receiving topical treatment with ultra-pure water, saline or other control and the other half receiving topical treatments of recombinant growth factors, exosomes (conditioned media) or PRP [29-37]. While the topical treatment with these mediums has produced varying degrees of success, the composition of PRP is still being determined, the size of growth factors can be prohibitive, and the use of CM leaves ambiguity for FDA intervention.

This leaves the field open for topical treatment of a synthetically produced, acellular product following microneedling or laser resurfacing. With the large-scale safety dataset of mRNA administration provided through the worldwide vaccination of Pfizer’s and Moderna’s mRNA vaccine, the application of topical mRNA should not warrant oversight by the FDA. The most significant hurdle is stabilizing the messenger RNA to be provided as a topical treatment. To this end, great strides are being explored to stabilize RNA for potential future vaccines (brand new paper).

Androgenic Alopecia

If this sounds interesting, we can further develop the story for the rejuvenation of dermal papillae with microneedling and topical treatment of mRNA.

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