Skin Cell Proliferation Stimulated by Microneedles

Abstract

A classical wound may be defined as a disruption of tissue integrity. Wounds, caused by trauma from accidents or surgery, that close via secondary intention rely on the biological phases of healing, i.e., hemostasis, inflammation, proliferation, and remodeling (HIPR). Depending on the wound type and severity, the inflammation phase begins immediately after injury and may last for an average of 7-14 days. Concurrent with the inflammation phase or slightly delayed, cell proliferation is stimulated followed by the activation of the remodeling (maturation) phase. The latter phase can last as long as 1 year or more, and the final healed state is represented by a scar tissue, a cross-linked collagen formation that usually aligns collagen fibers in a single direction. One may assume that skin microneedling that involves the use of dozens or as many as 200 needles that limit penetration to 1.5 mm over 1 cm 2 of skin would cause trauma and bleeding followed by the classical HIPR. However, this is not the case or at least the HIPR phases are significantly curtailed and healing never ends in a scar formation. Conversely dermabrasion used in aesthetic medicine for improving skin quality is based on ''ablation'' (destruction or wounding of superficial skin layers), which requires several weeks for healing that involves formation of new skin layers. Such procedures provoke an acute inflammatory response. We believe that a less intense inflammatory response occurs following microneedle perforation of the skin. However, the mechanism of action of microneedling appears to be different. Here we review the potential mechanisms by which microneedling of the skin facilitates skin repair without scarring after the treatment of superficial burns, acne, hyperpigmentation, and the non-advancing periwound skin surrounding the chronic ulcerations of the integument. Ó 2013 Elsevier Inc. All rights reserved. Potential Mechanism of Microneedle Treatment of Normal SkinSome explanations can be found with a closer look at enhanced cell communication and motility by endogenous electrical signals (electro-taxis). Dunkin et al 1 found that skin cuts to a depth of 0.5-0.6 mm close by electrical cell stimulation without any trace of scar tissue. Zhao et al 2 reported similar effects of electrical currents on cell motility and healing. Deeper skin cuts close by ''skin repair'' that ultimately results in scar formation Figure 1.In 2010 Liebl proposed that microneedling could be used in treating chronic wounds. In reviewing the literature related to wound healing by electric field stimulation, he theorized that the mechanisms for the main action of microneedling may include trans-epithelial potentials (TEPs) and the skin battery. 3 Foulds and Barker 4 placed electrodes on the stratum corneum (SC) and inside the dermis, and measured a negative potential difference of the SC ranging from 10 to 60 mV, and averaging 223.4 mV (Figure 2).

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Retrospective observational cohort study on cosmetic outcome of using Ti‑Ni memory alloy wire for intradermal suture following mastectomy in patients with breast cancer

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Microneedles for drug delivery: trends and progress

“…As mentioned earlier, MNs have been proposed as an alternative delivery method to TDPs and hypodermic syringes as they have shown to overcome the various short comings previously outlined. Indeed, it has been illustrated by Benson & Namjoshi (2008) and many other researchers (Li et al, 2011b;Shah et al, 2011;Liebl & Kloth, 2012) that MN research is a promising field of research to be pursued more extensively as it can be used to overcome the skin's natural defensive barrier, the SC, in both adults and children. The rate of release of the drug depends upon the controlling membrane of the TDP (Osborne et al, 2013), and therefore ensuring a consistent drug release profile can be uncertain.…”