Basil M. Hantash

Bipolar fractional radiofrequency treatment induces neoelastogenesis and neocollagenesis

We recently introduced Renesis™, a novel minimally invasive radiofrequency (RF) device, for the treatment of human skin. The wound healing response post‐fractional RF (FRF™) treatment was examined in human subjects.

Laser-induced transepidermal elimination of content by fractional photothermolysis

The wound healing process in skin is studied in human subjects treated with fractional photothermolysis. In-vivo histological evaluation of vacuoles formed over microthermal zones (MTZs) and their content is undertaken. A 30-W, 1550-nm single-mode fiber laser system delivers an array of 60 microm or 140 microm 1e2 incidence microbeam spot size at variable pulse energy and density. Treatments span from 6 to 20 mJ with skin excisions performed 1-day post-treatment. Staining with hematoxylin and eosin demonstrates an intact stratum corneum with vacuolar formation within the epidermis. The re-epithelialization process with repopulation of melanocytes and keratinocytes at the basal layer is apparent by 1-day post-treatment. The dermal-epidermal (DE) junction is weakened and separated just above zones of dermal coagulation. Complete loss of dermal cell viability is noted within the confines of the MTZs 1-day post-treatment, as assessed by lactate dehydrogenase. All cells falling outside the irradiation field remain viable. Content within the epidermal vacuoles stain positively with Gomori trichrome, suggesting a dermal origin. However, the positive staining could be due to loss of specificity after thermal alteration. Nevertheless, this dermal extrusion hypothesis is supported by very specific positive staining with an antihuman elastin antibody. Fractional photothermolysis creates microthermal lesions that allow transport and extrusion of dermal content through a compromised DE junction. Some dermal material is incorporated into the microepidermal necrotic debris and shuttled up the epidermis to eventually be exfoliated through the stratum corneum. This is the first report of a nonablative laser-induced transport mechanism by which dermal content can be predictably extruded biologically through the epidermis. Thus, treatment with the 1550-nm fiber laser may provide the first therapeutic option for clinical indications, including pigmentary disorders such as medically recalcitrant melasma, solar elastosis, as well as depositional diseases such as mucinosis and amyloidosis.

Pilot clinical study of a novel minimally invasive bipolar microneedle radiofrequency device

Noninvasive bipolar and monopolar radiofrequency (RF) deep dermal heating devices have previously been described. A novel minimally invasive RF device employing a bipolar microneedle electrode system is introduced and its resultant thermal effects on human skin in vivo were characterized for the first time.

Short-Sequence Oligopeptides with Inhibitory Activity against Mushroom and Human Tyrosinase

Cutaneous hyperpigmentation is a common disorder due to excess melanin production by the enzyme tyrosinase. The gold standard for treatment is hydroquinone (HQ), which reduces pigmentation through its toxicity to melanocytes rather than via tyrosinase inhibition. We screened an internal library for oligopeptides that inhibited both mushroom and human tyrosinase but showed no cytotoxicity to human melanocytes. We identified two highly active inhibitory sequences, P3 and P4, of 8- and 10-amino-acid-length, respectively. Mushroom tyrosinase inhibition was dose-dependent with IC(50) (half-maximal inhibitory concentration) values of 123 and 40 microM, respectively, compared with 680 microM for HQ. Other oligopeptides showed weaker or no inhibitory activity. Kinetic studies showed that P3 and P4 are competitive inhibitors of mushroom tyrosinase. At 100 microM, P3 and P4 inhibited human tyrosinase by 25-35%. This inhibition partially depended on whether L-dopa or L-tyrosine was the substrate, suggesting that tyrosinase may contain contains two distinct catalytic sites. Treatment of melanocytes with 100 microM P3 or P4 for 7 days led to a 27 or 43% reduction in melanin content. This inhibition was independent of cell proliferation and cytotoxic effects. Our data suggest that peptide-mediated inhibition of melanogenesis is due to reduction in tyrosinase activity.

Advances in the treatment of melasma: a review of the recent literature.

Background Melasma is an acquired pigmentary disorder classically manifesting as symmetric hyperpigmented macules and patches on the face. It most commonly affects women of reproductive age with darker skin tones but may also affect adolescents, older women, and men. Although its pathogenesis remains unclear, known risk factors include ultraviolet radiation, hormonal variations of pregnancy, thyroid disease, oral contraceptives, and antiseizure medications. Hydroquinone‐containing topical agents are the current standard for melasma treatment, but concern about side effects and long‐term safety has spurred efforts to develop alternative treatment options. Objectives To review recent advances in melasma treatment. Materials and Methods MEDLINE was searched from 2006 to the present for randomized controlled trials (RCTs) of melasma treatments. Results Nineteen published RCTs were found covering interventions such as topical therapies, chemical peels, and electromagnetic devices. The outcomes of the studies were summarized into tabular form for easy reference and comparison. Conclusions Although melasma is difficult to treat, novel therapeutic modalities have emerged. Further RCT need to be performed to better assess the safety and efficacy of these novel treatment modalities, especially for the long‐term maintenance of melasma.

Split‐Face Comparison of the Erbium Micropeel with Intense Pulsed Light

BACKGROUND A variety of photorejuvenative techniques have been utilized to reverse the signs of cutaneous photoaging, including ablative and nonablative laser resurfacing as well as light-based devices. OBJECTIVE The purpose of this split-face randomized prospective open-label trial was to determine the effectiveness of sequential erbium:yttrium-aluminum-garnet (Er:YAG) laser versus intense pulsed light (IPL) for the treatment of mild to moderate facial photodamage. MATERIALS AND METHODS Ten subjects (ages 35–63) with facial dyschromia and rhytides were enrolled. Study patients were randomized to the two treatment arms, Er:YAG (3.8 J/cm2, 30% pattern overlap, 0% interpulse overlap, 15 μm per pass with no coagulation) and IPL (560-nm filter, 30 J/cm2, 2.4/4.0-ms pulse with 10-ms delay), each receiving three sequential treatments spaced 1 month apart. Subjective and blinded physician evaluations were performed at baseline and 4, 8, and 20 weeks posttreatment using a nominal scale from 1 to 4. Erythema and adverse events were assessed 1 week following each treatment. RESULTS Ten female subjects with mild to moderate facial photodamage were treated with one pass of either IPL or Er:YAG in a split-face fashion. Patients received three treatments each spaced 1 month apart. Nine of 10 patients completed the trial; 1 withdrew due to pain during the second Er:YAG treatment. Basline subjective and blinded physician dyschromia and rhytid scores revealed no significant difference between the IPL and Er:YAG randomly assigned sides. Up to three IPL or Er:YAG treatments did not result in a significant improvement in rhytid scores. Subjective and blinded physician dyschromia scores improved 26 and 38%, respectively, 3 months after the final IPL treatment, but only by 7 and 29%, respectively, with Er:YAG. Subjective global facial appearance scores worsened by 5% while blinded physician scores improved by 16% 3 months after 3 Er:YAG treatments, but by 28 and 20% for IPL, respectively. The overall incidence of adverse events and subsequent downtime was increased for Er:YAG (1/10 patients experienced hyperpigmentation, 3/10 exfoliation, 1/10 blistering, and 5/10 discomfort) compared to IPL (1/10 exfoliation and 1/10 discomfort), although no permanent side effects were observed with either treatment arm. CONCLUSIONS While low-fluence erbium resurfacing has a modest effect on facial photodamage, patients preferred IPL because it resulted in less downtime.

Support of human adipose-derived mesenchymal stem cell multipotency by a poloxamer-octapeptide hybrid hydrogel

The development of new biological materials, particularly those capable of serving as permissive substrates for cell growth, differentiation, and biological function, is a key area for advancing medical technology. In this work, we examined the characteristics of a hybrid hydrogel scaffold composed of poloxamer 407 (PO) and the self-assembling oligopeptdide EFK8 in vitro and in vivo. Rheological tests showed that the storage modulus of EFK8-PO increased by 4 orders of magnitude compared to that of EFK8 alone, indicating that EFK8-PO integrates POs high and tunable mechanical strength and integrity with the superior bioactivity of EFK8. When human adipose-derived mesenchymal stem cells (hAMSCs) were cultured in PO, we observed severe aggregation. Conversely, almost no aggregation was observed in EFK8 or EFK8-PO after 6 days of culture. hAMSC viability in all 3 hydrogels remained above 80% after 2 weeks of culture. EFK8 and EFK8-PO significantly increased hAMSC proliferation rates. In addition, EFK8- and EFK8-PO- but not PO encapsulated hAMSCs differentiated into adipocytes or osteoblasts when exposed to appropriate induction medium, suggesting EFK8 supports hAMSC multipotency in vitro. Moreover, only EFK8-PO supported hAMSC engraftment and adipogenic differenitiation post-transplantation into nude mice. Immunohistochemical analysis confirmed the new tissue was human in origin. Our studies show that EFK8-PO maintains improved mechanical properties and bioactivity relative to its individual constituents, supporting its potential use as a stem cell scaffold in soft tissue engineering.

Differential expression of stem cell markers in human follicular bulge and interfollicular epidermal compartments

Although skin contains a number of stem cell repositories, their characterization has been hindered by a lack of specific markers and an unclear in vivo localization. In this study, we whole mounted single human scalp hair follicles and examined their profiles using in situ immunohistochemistry and multicolor immunofluorescence in search of markers to distinguish between stem cells residing in the interfollicular epidermis (IFE) and bulge. Our study revealed that expression of several biomarkers localized uniquely to the basal IFE (CD34 and CD117), bulge region (CD200), or both (CK15, CD49f, and CD29). In addition, we found that both basal IFE and bulge stem cells did not express CD71 or CD24 suggesting their potential utility as negative selection markers. Dermal papilla but not basal IFE or bulge stem cells expressed CD90, making it a potential positive selection marker for dermal hair follicle stem cells. The markers tested in this study may enable pursuit of cell sorting and purification strategies aimed at determining each stem cell population’s unique molecular signature.

Bioactive oligopeptides in dermatology: Part II

Peptides are central to the regulation and modulation of the chemical reactions and biological responses that occur in nature. Many physiological processes are affected by the interactions of these peptides, including cell proliferation and migration, inflammation, melanogenesis, angiogenesis and innate immunity. Thus, biologically active peptides offer a great potential medically and therapeutically. Moreover, the ability to generate synthetic peptides with attention to specifically modulating their pharmacokinetics and properties for increased potency, delivery and stability has spurred much interest in this rapidly growing field of research. In this review, we focus on the therapeutic uses of bioactive peptides as antimicrobials and effectors of neurotransmitter release. We also highlight the advantages and challenges associated with this new technology and discuss methods for improving oligopeptide transdermal delivery.

Cellular Regulation of Sodium‐Calcium Exchange

Abstract: Na+/Ca2+ exchange activity was studied in transfected Chinese hamster ovary (CHO) cells expressing the wild‐type cardiac exchanger (NCX1.1) or mutants created by site‐directed mutagenesis. The activity of the wild‐type exchanger, but not exchanger mutants deficient in Ca2+‐dependent activation, was inhibited by sphingolipids such as ceramide and sphingosine. We propose that sphingolipids interfere with the regulatory activation of exchange activity by Ca2+ and suggest that this interaction provides a means for monitoring and regulating diastolic Ca2+ levels in beating cardiac myocytes. Exchange activity in CHO cells was also linked, through a poorly understood feedback mechanism, to Ca2+ accumulation within internal stores such as the endoplasmic reticulum and the mitochondria. Finally, the F‐actin cytoskeleton was shown to modulate exchange activity through interactions involving the exchangers central hydrophilic domain. We conclude that regulation of exchange activity in intact cells involves multiple interactions with various lipid species, cytosolic Ca2+, organellar Ca2+ stores, and the cytoskeleton.