Several papers have been published that evaluated the effects of microdermabrasion microscopically. Improvement of the stratum corneum is a common finding. One study showed it to have smoothed and become more compacted with epidermal hyperplasia [7]. In another study, where histology was performed immediately after treatment (acute) and after six procedures, found that acutely the stratum corneum was thinned with focal compaction and homogenization, but after six sessions, change was not seen in the stratum corneum, but the epidermis had thickened [8]. Freedman also demonstrated the thickening of the epidermis, a normalization of the “basket weave” appearance to the stratum corneum and a flattening and widening of the rete pegs [9]. Improved epidermal atrophy, horny plugs, loss of polarity, and basal cell liquefaction have been reported [7]. Another investigator found thinning of the epidermis, increased orthokeratosis, and decreased rete ridge pattern [10]. Moy described epidermal changes he felt were suggestive of hydration of keratinocytes [5].
One study on skin barrier changes with microdermabrasion showed improved hydration of the newly generated stratum corneum after microdermabrasion, with no change in sebum secretion [11]. Another study of serial microdermabrasion found a significantly significant increase in the ceramide level of the stratum corneum after serial microdermabrasion, and a trend toward improved lipid-barrier function [12]. Interestingly, two studies found, in contrast that there was no alteration of the stratum corneum by their methodology [8,13]. Molecular analysis following a single microdermabrasion failed to show an increased expression of the enzymes acetyl coenzyme carboxylase or 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase suggesting that in the stratum, corneum was unaltered, and that there was no stimulation of epidermal repair [13]. Such divergent results suggest a need for standardization of treatment parameters, but given the variation in equipment and techniques, this may be difficult indeed.
Perhaps even more important to discernable skin rejuvenation would be evidence of dermal effects. Three studies documented an increase in elastic fibers in the dermis [5,8,9]. Another showed improvement of elastosis in the dermis [7 ] . These types of changes could signal a benefit for not only photoaging, but for striae as well. Changes in dermal collagen have been documented microscopically. Comite showed an increase in organized collagen [14]. An immunohistochemical study found increased staining for Type I collagen in the papillary dermis [5]. Papillary dermal edema has been demonstrated [6,10]. Papillary dermal hyalinization and new collagen fibers were also found in Freedman’s study9. Return of collagen fibers to a more fibrillar appearance has also been reported [7]. Demonstrable overall increases in dermal collagen have been observed [9 ] 14]. Freedman’s results also showed an increase in fibroblasts, appearing larger and more dense in number, especially near dermal capillaries. Interestingly, Tan and associates’ histology studies did not show any significant change in dermal elastin or collagen content, again highlighting the variability of technique and results [10].
Improvement in microscopic parameters regarding pigment would also be an important finding for clinical improvement of the skin’s appearance. More regular distribution of melanosomes and less melanization of the epidermis was observed in one study [8]. Clinical brightening of irregular pigment could be the result of this biologic effect. Two investigators found vascular ectasia and a dermal perivascular infiltrate [9,10]. The clinical benefits of these microscopic changes would be the “glow” so often attributed to microdermabrasion.
When other factors have been studied, increases in skin temperature and increased blood flow post treatment via skin thermography have been documented [10]. The same paper looked at other mechanical alterations and found a decrease in sebum immediately posttreatment, improved skin elasticity, and improved skin compliance (less stiffness) after 5-6 sessions. Extensive biochemical and immunohistological analyses after a single microdermabrasion showed activation transcription factors activator protein AP-1 and nuclear factor NF-kB, which regulate the expression of many genes involved in inflammation,
wound healing, growth, differentiation, and apoptosis [13]. In addition, the same study showed substantial elevations in interleukin IL-1 в and tumor necrosis factor TNF-a gene expression, as well as that of three matrix metalloproteinases, MMP-1 (interstitial collage- nase) MMP-3 (stromelysin-1), and MMP-9 (gelatinase-B). These findings could suggest that microdermabrasion can facilitate extracellular dermal matrix repair. The corresponding clinical benefit of this finding is obvious.