Characterization and ex vivo evaluation of excised skin samples as substitutes for human dermal barrier in pharmaceutical and dermatological studies.

BACKGROUND: Excised animal and human skins are frequently used in permeability testing in pharmaceutical research. Several factors exist that may have influence on the results. In the current study some of the skin parameters that may affect drug permeability were analysed for human, mouse, rat and pig skin. MATERIALS AND METHODS: Classic biophysical skin parameters were measured (e.g. pH, hydration, permittivity, transepidermal water loss). Physiological characteristics of the skins were also analysed by confocal Raman spectroscopy, scanning electron microscopy and two-photon microscopy. RESULTS: Based on biophysical testing, skin barrier function was damaged in psoriatic mouse skin and in marketed pig skin. Hydration and pH values were similar among the species, but freezing and thawing reduced the water content of the skins and shifted the surface pH to acidic. Aging reduced hydration and permittivity, resulting in impaired barrier function. Mechanical sensitization used in permeability studies resulted in proportional thinning of dead epidermis. DISCUSSION: Results indicate that depending on the scientific question it should be considered whether fresh or frozen tissue is used, and for certain purposes rodent skins are well usable. The structure of the skin tissue (ceramide, cholesterol, keratin, natural moisturizing factor or urea) is similar in rats and mice, but due to the higher skin thickness the lipid distribution is different in porcine skin. Psoriasis led to irregular chemical composition of the skin. CONCLUSION: A comprehensive evaluation of skin samples of four species was performed. The biophysical and microscopic observations should be considered when selecting drug penetration models and experimental conditions.

[Limb saving surgery in cases of bone sarcomas]. / Végtagmegtartó mûtétek csontsarcomáknál.

At the Orthopedic Department of Semmelweis University we operate an internationally recognized bone and soft tissue tumor center. Our specialty is the treatment of benign and malignant bone tumors, tumor-like lesions and surgery of soft tissue tumors. Our main aim, taking into account the appropriate oncologic radicality, is to create the conditions for the development of limb saving surgery. Limb saving surgery is an interdisciplinary activity both in diagnosis and in treatment. We have proper pathology, radiology and interventional radiology background for the fast and advanced pathomorphological and radiomorphological diagnosis of different tumors. Using modern chemotherapy, radiotherapy and other advanced cancer treatment protocols rapid access to oncology background is provided for children and adults as well, both primary and secondary bone tumors and soft tissue sarcoma cases of the extremities. The limb saving surgery after removal of the tumor is essentially a reconstructive surgery. Reconstructive surgery in childhood and younger ages mean mainly the biological solutions (vascularized autologus bone grafts and/or homologous bone graft), otherwise in elderly ages implantation of tumor endoprostheses has a greater significance. Furthermore, the final tumor surgery requires experienced abdominal surgeon, vascular surgeon and plastic surgeon to ensure the background as well. The professional background of our clinical practice is based on participating in international conferences and spending several months abroad in different big tumor centers. Over the past 15 years, several international cancer congresses were organized in Hungary by our Department.

[The application of negative pressure wound therapy (NPWT) in potentially lethal conditions]. / A negatív nyomással végzett sebkezelés (NPWT) alkalmazása potenciálisan letális állapotokban.

Bemutatásra kerülo esetünkben egy 47 éves, generalizált septicus állapotú férfi beteg komplex terápiás megoldást igénylo kezelését ismertetjük, negatív nyomásterápia segítségével (NPWT). A páciens kezeletlen diabéteszes láb szindróma talaján kialakult szepszis, fasciitis necrotisans klinikai-radiomorfológiai képével került osztályunkra, akinél sürgosséggel feltárást, az alsó végtag valamennyi kompartmentjét érinto fasciotomiát végeztünk, NPWT-kezelést indítottunk. Kezelése során a beteg állapotát súlyosbító szövodmények léptek fel: Curling-fekély, toxicus epidermalis necrolysis (TEN). A fascitis kapcsán kialakult kb. 6% TBSA (total body surface area) kiterjedésu hámhiányt a TEN-szindróma további epidermális állományvesztéssel tovább súlyosbította. Állapotstabilizálást, kezdeti lokalis kontroll biztosítását követoen a hámhiányos felület csökkentése érdekében a sebeket szukítettük, a feltisztult sebalapok fedése 1:3 arányban hálósított félvastag bor transzplantációjával történt. Az NPWT-kezelést a transzplantációt követoen is folytattuk. A beteg három hónapos intenzív osztályos és sebészeti kezelést követoen sebészi szempontból meggyógyult. A negatív nyomásterápia korai - a kórlefolyásnak megfelelo - adekvát üzemmódban és fedési technikával történo alkalmazása a végtagvesztéssel és életveszéllyel járó nagy fokú hámhiány esetében hatékony eszköznek bizonyult. A multidiszciplináris terápiának köszönhetoen betegünk sebészeti alapbetegségét sikeresen gyógyítottuk, azonban az évtizedes tartamú kezeletlen cukorbetegsége, SARS-Covid peumoniája, a relabáló septicus állapota során fellépo szövodmények következtében felépülni már nem tudott.

Structural and Functional Analysis of Excised Skins and Human Reconstructed Epidermis with Confocal Raman Spectroscopy and in Microfluidic Diffusion Chambers.

Several ex vivo and in vitro skin models are available in the toolbox of dermatological and cosmetic research. Some of them are widely used in drug penetration testing. The excised skins show higher variability, while the in vitro skins provide more reproducible data. The aim of the current study was to compare the chemical composition of different skin models (excised rat skin, excised human skin and human-reconstructed epidermis) by measurement of ceramides, cholesterol, lactate, urea, protein and water at different depths of the tissues. The second goal was to compile a testing system, which includes a skin-on-a-chip diffusion setup and a confocal Raman spectroscopy for testing drug diffusion across the skin barrier and accumulation in the tissue models. A hydrophilic drug caffeine and the P-glycoprotein substrate quinidine were used in the study as topical cream formulations. The results indicate that although the transdermal diffusion of quinidine is lower, the skin accumulation was comparable for the two drugs. The various skin models showed different chemical compositions. The human skin was abundant in ceramides and cholesterol, while the reconstructed skin contained less water and more urea and protein. Based on these results, it can be concluded that skin-on-a-chip and confocal Raman microspectroscopy are suitable for testing drug penetration and distribution at different skin layers within an exposition window. Furthermore, obese human skin should be treated with caution for skin absorption testing due to its unbalanced composition.

Development and Evaluation of a Human Skin Equivalent in a Semiautomatic Microfluidic Diffusion Chamber.

There is an increasing demand for transdermal transport measurements to optimize topical drug formulations and to achieve proper penetration profile of cosmetic ingredients. Reflecting ethical concerns the use of both human and animal tissues is becoming more restricted. Therefore, the focus of dermal research is shifting towards in vitro assays. In the current proof-of-concept study a three-layer skin equivalent using human HaCaT keratinocytes, an electrospun polycaprolactone mesh and a collagen-I gel was compared to human excised skin samples. We measured the permeability of the samples for 2% caffeine cream using a miniaturized dynamic diffusion cell ("skin-on-a-chip" microfluidic device). Caffeine delivery exhibits similar transport kinetics through the artificial skin and the human tissue: after a rapid rise, a long-lasting high concentration steady state develops. This is markedly distinct from the kinetics measured when using cell-free constructs, where a shorter release was observable. These results imply that both the established skin equivalent and the microfluidic diffusion chamber can serve as a suitable base for further development of more complex tissue substitutes.