Human Skin Cell Cultures Research Articles

An oil-in-water emulsion containing a combination of ginger extract and synthetic cannabidiol with potent in vitro anti-inflammatory effects alleviates symptoms of atopic dermatitis in a clinical trial.

Atopic dermatitis (AD) is a highly prevalent chronic skin disease. Anti-inflammatory and antipruritic emollients (emollients plus) with excellent cosmetic properties may alleviate AD-related symptoms and reduce the number of exacerbations. To screen for herbal extracts with potent anti-inflammatory and antioxidative potential in human skin cell cultures. Ginger extract and synthetic cannabidiol (CBD) were identified and combined in the cosmetic product BNO 3731, which was evaluated in a randomized clinical trial. Preclinical: anti-inflammatory effects of ginger extract, synthetic CBD and a combination thereof were evaluated in human skin cell cultures by analysing nuclear factor κB activation, release of inflammatory cytokines and endocannabinoid production. Clinical: BNO 3731 was studied in a clinical trial comprising 44 AD patients (adults and children) and compared to a benchmark product over a treatment duration of five days. Symptom severity was evaluated by objective and subjective dermatological assessments as well as physiological skin parameters. Itch intensity was assessed using a numerical rating scale (NRS-11). Preclinical: Ginger extract and synthetic CBD exhibited potent anti-inflammatory and antioxidative effects in vitro which were associated with elevated concentrations of the endocannabinoid, anandamide. Clinical: BNO 3731 significantly alleviated symptoms of AD and improved physiological skin parameters. Itch intensity decreased significantly by 55%, and in 75% of subjects, itch improved ≥2 points on the NRS-11 scale. No adverse events were reported. BNO 3731, containing a unique synergistic combination of ginger extract and synthetic CBD, is an effective and safe treatment option for dry and eczema-prone skin, providing rapid and substantial relief of pruritus.

Comprehensive Physicochemical Characterization, In Vitro Membrane Permeation, and In Vitro Human Skin Cell Culture of a Novel TOPK Inhibitor, HI-TOPK-032.

Nonmelanoma skin cancers (NMSC) are the most common skin cancers, and about 5.4 million people are diagnosed each year in the United States. A newly developed T-lymphokine-activated killer cell-originated protein kinase (TOPK) inhibitor, HI-TOPK-032, is effective in suppressing colon cancer cell growth, inducing the apoptosis of colon cancer cells and ultraviolet (UV) light-induced squamous cell carcinoma (SCC). This study aimed to investigate the physicochemical properties, permeation behavior, and cytotoxicity potential of HI-TOPK-032 prior to the development of a suitable topical formulation for targeted skin drug delivery. Techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, differential scanning calorimetry (DSC), hot-stage microscopy (HSM), X-ray powder diffraction (XRPD), Karl Fisher (KF) coulometric titration, Raman spectrometry, confocal Raman microscopy (CRM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and Fourier transform infrared microscopy were used to characterize HI-TOPK-032. The dose effect of HI-TOPK-032 on in vitro cell viability was evaluated using a 2D cell culture of the human skin keratinocyte cell line (HaCaT) and primary normal human epidermal keratinocytes (NHEKs). Transepithelial electrical resistance (TEER) at the air-liquid interface as a function of dose and time was measured on the HaCAT human skin cell line. The membrane permeation behavior of HI-TOPK-032 was tested using the Strat-M® synthetic biomimetic membrane with an in vitro Franz cell diffusion system. The physicochemical evaluation results confirmed the amorphous nature of the drug and the homogeneity of the sample with all characteristic chemical peaks. The in vitro cell viability assay results confirmed 100% cell viability up to 10 µM of HI-TOPK-032. Further, a rapid, specific, precise, and validated reverse phase-high performance liquid chromatography (RP-HPLC) method for the quantitative estimation of HI-TOPK-032 was developed. This is the first systematic and comprehensive characterization of HI-TOPK-032 and a report of these findings.

The Combination of Synoeca-MP Antimicrobial Peptide with IDR-1018 Stimulates Proliferation, Migration, and the Expression of Pro-Regenerative Genes in Both Human Skin Cell Cultures and 3D Skin Equivalents.

In skin lesions, the development of microbial infection affects the healing process, increasing morbidity and mortality rates in patients with severe burns, diabetic foot, and other types of skin injuries. Synoeca-MP is an antimicrobial peptide (AMP) that exhibits activity against several bacteria of clinical importance, but its cytotoxicity can represent a problem for its positioning as an effective antimicrobial compound. In contrast, the immunomodulatory peptide IDR-1018 presents low toxicity and a wide regenerative potential due to its ability to reduce apoptotic mRNA expression and promote skin cell proliferation. In the present study, we used human skin cells and a 3D skin equivalent models to analyze the potential of the IDR-1018 peptide to attenuate the cytotoxicity of synoeca-MP, as well as the influence of synoeca-MP/IDR-1018 combination on cell proliferation, regenerative processes, and wound repair. We found that the addition of IDR-1018 significantly improved the biological properties of synoeca-MP on skin cells without modifying its antibacterial activity against S. aureus. Likewise, in both melanocytes and keratinocytes, the treatment with synoeca-MP/IDR-1018 combination induces cell proliferation and migration, while in a 3D human skin equivalent model, it can accelerate wound reepithelization. Furthermore, treatment with this peptide combination generates an up-regulation in the expression of pro-regenerative genes in both monolayer cell cultures and in 3D skin equivalents. This data suggests that the synoeca-MP/IDR-1018 combination possesses a good profile of antimicrobial and pro-regenerative activity, opening the door to the development of new strategies for the treatment of skin lesions.

Surface modification of film chitosan materials with aldehydes for wettability and biodegradation control

Chitosan is one of the prospective polymers for use in regenerative medicine which has unique properties such as biocompatibility, biodegradability, antimicrobial, anti-inflammatory, and antitumor potency. In this article, we study the peculiarities of the surface modification of chitosan films with carbonyl-containing compounds, which differed both in molecular characteristics and in their hydrophilic and hydrophobic properties. The potential for controlling the biodegradation of the resulting materials has been established, which can be used in the creation of wound dressings. Both the destruction time and lyophilic properties of the surface depend on the length of the modifier’s hydrocarbon radical. The contact angle and water absorption of obtained film materials correlate with hydrophobicity, which estimated by the calculated value of the hydrophilic–lipophilic balance. The cytotoxicity of modified chitosan films was studied, and it was found that they are non-toxic (cytotoxic index of < 50%) for human skin cell cultures, which shows their potential for use in the creation of materials for skin protection and external wound healing.

Impact of fabrics from transgenic flax on cultures of skin cells

The development of a new type of wound dressing material that can support skin regeneration is an important challenge to improve treatment of chronic, non-healing wounds. The objective of this study was to compare the impact of flax fabrics from transgenic plants overexpressing phenolic acids and flavonoids (W92) and polyhydroxybutyrate (M48), as well as fabric from non-transgenic plant (Nike) on cultures of human skin cells. Flax fabric pieces as well as water extracts from the fabrics were co-cultured with human skin cells: keratinocytes, fibroblasts, dermal microvascular endothelial cells, and with monocytoid cell line (THP1) for 48 h. Cell viability and proliferation were assessed with the sulforhodamine B colorimetric assay. Intracellular reactive oxygen species (ROS) was estimated with the 2'7 dichlorodihydrofluorescein diacetate (DCFH-DA) oxidation method. Endothelial cell migration was measured with the scratch assay. The results were compared with the multi-criteria analysis (MCA) procedure. Tested flax fabrics released flavonoids and polyhydroxybutyrate to cell culture media, as it was determined by means of the high performance liquid chromatography (HPLC) method. Fabrics from transgenic plants W92 and M48 promoted proliferation of keratinocytes and fibroblasts. Water extracts from flax fabric diminished the proliferation of monocytoid cells, decreased oxidative burst in activated THP1 cells and accelerated the velocity of dermal microvascular cell migration. The MCA proved that the sum of beneficial effects estimated in human skin cell cultures was higher (by 47% and by 34% with W92 and M48, respectively) than that of non-transgenic flax fabric (Nike). The W92 and M48 fabrics should be further studied as candidates for elaboration of new types of bandages, able to improve skin wound healing.

Calendula officinalis Protection Against Cytotoxicity Effects of Personal Care Products on HaCaT Human Skin Cells

Background: Human skin is normally exposed to ionizing and UV radiations and on occasions it may also be subjected to beauty products or drugs that the host uses; all of which can generate reactive oxygen species (ROS). Objective: In this study, Calendula officinalis extract, which contains antioxidant compounds, was examined for its protective effects against the products that generate ROS- induced cytotoxic activity towards human skin cells. Methodology: The protection against cytotoxicity by Calendula officinalis extract was investigated in vitro using a dose-response on HaCaT human skin cells. The proprietary aqueous calendula extract C from biodynamically grown plant was examined. Protection against cytotoxicity was measured via the methyl tetrazolium cytotoxicity (MTT) assay. Cells were exposed to the calendula extracts for 48h before being exposed to personal care products consisting of two head lice treatments -Lice Breaker (Permethrin 1% w/w) and Organix Pyrethrum treatment (4 g/L Pyrethrins, 16 g/LPiperonyl Butoxide) and two beauty products -Nivea Visage Q10 plus Anti-Wrinkle face moisturizer + TiO2; and Nivea Visage Q10 Plus Anti-Wrinkle face moisturizer (without TiO2) for 1h. Results: The effect of different concentrations of calendula extract on HaCaT human skin cells in vitro was explored. Doses of 1% (v/v) [1.4 mg dry weight equiv/ml] or less showed no toxicity. Cells were also exposed to the calendula extract for 48 hours before being exposed to the four personal care products for 1h. using the MTT cytotoxicity assay; it was observed that extract of Calendula officinalis gave time-dependent and concentrationdependent protection against harmful products that induce cell killing. Pre-incubation with the calendula extract for 48 hours significantly increased survival relative to the population without the extract by 30% and 47.4%, respectively, following treatment with personal care products. Conclusion: This study demonstrates that calendula extract contains bioactive and free radical scavenging compounds that significantly protect against personal care products that generate oxidative stress cytotoxicity in a human skin cell culture model.

In vitro growth, cytopathic effects and clearance of monolayers by clinical isolates of Balamuthia mandrillaris in human skin cell cultures

Balamuthia mandrillaris is a free-living ameba (FLA) that has been isolated or its DNA identified in soil, dust and water. It causes a fatal central nervous system infection in humans and animals. Although it is environmental as Acanthamoeba and Naegleria fowleri, the two other free-living amebae that also cause CNS infections in humans and other animals, Balamuthia does not feed on bacteria as the other FLA. In the laboratory, it can be grown on a variety of mammalian cell cultures. In this study we examined the ability of three different Balamuthia isolates to grow on several different human skin cell cultures including the WT/A keratinocyte cell cultures. A corneal isolate of Acanthamoeba castellanii was used for comparison.

Extracts from Calendula officinalis Offer in Vitro Protection Against H2O2 Induced Oxidative Stress Cell Killing of Human Skin Cells

The in vitro safety and antioxidant potential of Calendula officinalis flower head extracts was investigated. The effect of different concentrations (0.125, 0.5, 1.0, 2.0 and 5.0% (v/v)) of Calendula extracts on human skin cells HaCaT in vitro was explored. Doses of 1.0% (v/v) (0.88 mg dry weight/mL) or less showed no toxicity. Cells were also exposed to the Calendula extracts for either 4, 24 or 48 h before being exposed to an oxidative insult (hydrogen peroxide H2 O2 ) for 1 h. Using the MTT cytotoxicity assay, it was observed that two independent extracts of C. officinalis gave time-dependent and concentration-dependent H2 O2 protection against induced oxidative stress in vitro using human skin cells. Pre-incubation with the Calendula extracts for 24 and 48 h increased survival relative to the population without extract by 20% and 40% respectively following oxidative challenge. The antioxidant potential of the Calendula extracts was confirmed using a complimentary chemical technique, the DPPH(●) assay. Calendula extracts exhibited free radical scavenging abilities. This study demonstrates that Calendula flower extracts contain bioactive and free radical scavenging compounds that significantly protect against oxidative stress in a human skin cell culture model.

Comparison of the effects between animal-derived trypsin and recombinant trypsin on human skin cells proliferation, gene and protein expression

Animal-derivative free reagents are preferred in skin cell culture for clinical applications. The aim of this study was to compare the performance and effects between animal-derived trypsin and recombinant trypsin for skin cells culture and expansion. Full thickness human skin was digested in 0.6 % collagenase for 6 h to liberate the fibroblasts, followed by treatment with either animal-derived trypsin; Trypsin EDTA (TE) or recombinant trypsin; TrypLE Select (TS) to liberate the keratinocytes. Both keratinocytes and fibroblasts were then culture-expanded until passage 2. Trypsinization for both cell types during culture-expansion was performed using either TE or TS. Total cells yield was determined using a haemocytometer. Expression of collagen type I, collagen type III (Col-III), cytokeratin 10, and cytokeratin 14 genes were quantified via RT-PCR and further confirmed with immunocytochemical staining. The results of our study showed that the total cell yield for both keratinocytes and fibroblasts treated with TE or TS were comparable. RT-PCR showed that expression of skin-specific genes except Col-III was higher in the TS treated group compared to that in the TE group. Expression of proteins specific to the two cell types were confirmed by immunocytochemical staining in both TE and TS groups. In conclusion, the performance of the recombinant trypsin is comparable with the well-established animal-derived trypsin for human skin cell culture expansion in terms of cell yield and expression of specific cellular markers.

Application of genomics to breakthroughs in the cosmetic treatment of skin ageing and discoloration

The use of global gene expression profiling, also known as transcriptomics or genomics, provides a means to identify key pathways affected in ageing skin that can be improved with appropriate cosmetic compounds. Aspects of skin ageing that can be addressed include matrix production, barrier, lipid synthesis, antioxidant capacity and hyperpigmentation. Gene expression profiling together with in vitro human skin cell cultures for compound screening and verification have led to the identification of cosmetic compounds and an understanding of the biological effects of compounds such as niacinamide, Pal-KTTKS, hexamidine, retinyl propionate and sodium dehydroacetate. In addition, understanding of the decreased antioxidant capacity of aged skin has led to the identification of new antiageing ingredients, olive-derived fatty acid ethoxylates, which have been shown to restore antioxidant enzymes in skin keratinocytes and fibroblasts. Gene expression profiling of age spots has also provided an understanding of the role of undecylenoyl phenylalanine in reducing melanin production by an adrenergic receptor mechanism in melanocytes. The use of these compounds in cosmetic formulations for skin care can aid improvements in the appearance of aged skin, including the improved appearance of fine lines, wrinkles and age spots.

Human Skin Cells That Express Stage-Specific Embryonic Antigen 3 Associate with Dermal Tissue Regeneration

Stage-specific embryonic antigen 3 (SSEA3) is a glycosphingolipid that has previously been used to identify cells with stem cell-like, multipotent, and pluripotent characteristics. A rare subpopulation of SSEA3-expressing cells exists in the dermis of adult human skin. These SSEA3-expressing cells undergo a significant increase in cell number in response to injury, suggesting a possible role in regeneration. These SSEA3-expressing regeneration-associated (SERA) cells were derived through primary cell culture, purified by fluorescence-activated cell sorting (FACS), and characterized. Longer in vitro culture of the primary skin cells led to lower SSEA3 expression stability after FACS-based purification, suggesting that the current culture conditions may need to be optimized to permit the large-scale expansion of SERA cells. The SERA cells demonstrated a global transcriptional state that was most similar to bone marrow- and fat-derived mesenchymal stem cells (MSCs), and the highest expressing SSEA3-expressing cells co-expressed CD105 (clone 35). However, while a rare population of MSCs was observed in primary human skin cell cultures that could differentiate into adipocytes, osteoblasts, or chondrocytes, SERA cells did not possess this differentiation capacity, suggesting that there are at least two different rare subpopulations in adult human skin primary cultures. The identification, efficient purification, and large-scale expansion of these rare subpopulations (SERA cells and MSCs) from heterogeneous adult human skin primary cell cultures may have applications for future patient-specific cellular therapies.

Volatile profiles of human skin cell cultures in different degrees of senescence

It is known that skin releases volatile organic compounds to the environment, and also that its emission pattern changes with aging of the skin. It could be considered, that these compounds are intermediaries in cell metabolism, since many intermediaries of metabolic pathways have a volatile potential. In this work, a simple and non-destructive method consisting of SPME sampling and GC/MS analysis was developed to identify volatile organic emanations from cell cultures. This technique, applied to skin cells culture, indicates that the cells or cell metabolism produce several skin emissions. Chemometric analysis was performed in order to explore the relationship between a volatile profile and the senescence of cell cultures. Volatile profiles were different for cell cultures in different degrees of senescence, indicating that volatile compound patterns could be used to provide information about the age of skin cells.

ELF Non Ionizing Radiation Changes the Distribution of the Inner Chemical Functional Groups in Human Epithelial Cell (HaCaT) Culture

Human skin cell culture (HaCaT) that has been exposed to an AC magnetic field undergoes detectable changes in its biochemical properties and shapes. Such changes were observed by infrared wavelength-selective scanning near-field optical microscopy with a resolution of 80–100 nm. We specifically investigated the changes in the distribution of the inner chemical functional groups and in the cell morphology induced by a 24 h exposure to a 1 mT (rms), 50 Hz sinusoidal magnetic field in a temperature regulated solenoid. These results further accentuate the crucial questions, raised by several recent studies, about the impact of low-frequency electromagnetic field on human cells.

Quantitative analysis of MC1R gene expression in human skin cell cultures

To address the issue of melanocortin-1 receptor (MC1R) expression in non-melanocytic cells, we have quantitatively evaluated the relative expression levels of both MC1R mRNA and protein in a subset of different cell types. Using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) at high cycle numbers, we detected MC1R mRNA in all cell types examined, including human embryonic kidney-293 (HEK 293) cells, a cell type widely used as a negative control in melanocortin expression studies. Quantitative real-time PCR revealed the highest levels of MC1R transcripts were in melanocytic cells, whereas the keratinocyte and fibroblast cell cultures examined had only a low level of expression, similar to that of HEK 293 cells. Antibody mediated detection of MC1R protein in membrane extracts demonstrated exogenous receptor in MC1R transfected cell lines, as well as endogenous MC1R in melanoma cells. However, radioligand binding procedures were required to detect MC1R protein of normal human melanocytes and no surface expression of MC1R was detected in any of the non-melanocytic cells examined. This was consistent with their low level of mRNA, and suggests that, if present, the levels of surface receptor are significantly lower than that in melanocytes. The capacity of such limited levels of MC1R protein to influence non-melanocytic skin cell biology would likely be severely compromised. Indeed, the MC1R agonist [NIe(4), D-Phe(7)] alpha-melanocyte stimulating hormone (NDP-MSH) was unable to elevate intracellular cyclic adenosine monophosphate (cAMP) levels in the keratinocyte and fibroblast cells examined, whereas a robust increase was elicited in melanocytes. Although there are a variety of cell types with detectable MC1R mRNA, the expression of physiologically significant levels of the receptor may be more restricted than the current literature indicates, and within epidermal tissue may be limited to the melanocyte.

Vaccinia Virus Induces Strong Immunoregulatory Cytokine Production in Healthy Human Epidermal Keratinocytes: a Novel Strategy for Immune Evasion

Iatrogenic cutaneous infection with vaccinia virus (VV) and naturally occurring systemic infection with variola virus both lead to the characteristic skin "pox" lesions. Despite significant medical experience with both viruses, surprisingly little is understood about the interactions between these poxviruses and healthy resident skin cells. In recent years, it has become clear that skin plays an essential role in modulating both innate and adaptive immune responses, in part by producing and responding to a variety of cytokines and chemokines upon stimulation. Antagonists of many of these compounds are encoded in poxvirus genomes. Infection of skin cells with poxvirus may lead to a unique pattern of cytokine and chemokine production that might alter the cutaneous immune surveillance function. In this study, we infected primary cultures of human skin cells with VV and monitored antigen expression, virus replication, and cytokine production from the infected cells. While T cells, Langerhans cells, and dermal dendritic cells were infected abortively, keratinocytes, dermal fibroblasts, and dermal microvascular endothelial cells (HMVEC-d) all supported the complete virus life cycle. In contrast to the robust viral replication in fibroblasts and HMVEC-d, only limited viral replication was observed in keratinocytes. Importantly, VV infection of keratinocytes led to up-regulation of immunoregulatory and Th2 cytokines, including transforming growth factor beta, interleukin-10 (IL-10), and IL-13. We propose that the rapid induction of keratinocyte Th2 and immunoregulatory cytokines represents a poxvirus strategy to evade immune surveillance, and the limited viral multiplication in keratinocytes may be a protective mechanism to help the immune system "win the race."

An approach for development of alternative test methods based on mechanisms of skin irritation

Recent advances in techniques for culture of human skin cells have led to their potential for use as in vitro models for skin irritation testing to augment or replace existing rabbit skin patch tests. Our work is directed towards the development of cultured human skin cells, together with endpoints that can be linked to in vivo mechanisms of skin irritation, as in vitro models for prediction of human skin irritation, and for study of mechanisms of contact irritant dermatitis. Three types of commercial human skin cell cultures have been evaluated, epidermal keratinocytes and partially or fully cornified keratinocyte—dermal fibroblast co-cultures. Human epidermal keratinocyte cultures (Clonetics) were treated with product ingredients and formulations, and the extent of cell damage was assessed by incorporation of the vital dye neutral red. Cell damage correlated with human skin patch data for ingredient chemicals with the exception of acids and alkalis, but did not correlate with skin irritation to surfactant-containing product formulations. Cultures of human skin equivalents were evaluated as potential models for measurement of responses to test materials that could not be measured in the keratinocyte/neutral red assay. We developed a battery of in vitro endpoints to measure responses to prototype ingredients and formulations in human epidermal keratinocyte—dermal fibroblast co-cultures grown on a nylon mesh (‘Skin 2’ from Advanced Tissue Sciences) or on a collagen gel (‘Testskin’ from Organogenesis). The endpoints measure cytotoxicity (neutral red and MTT vital dye staining, lactate dehydrogenase and N-acetyl glucosaminidase release, glucose utilization) and inflammatory mediator (prostaglandin E 2) release. Initial experiments indicate a promising correlation between responses of the Skin 2 model to prototype surfactants and in vivo human skin irritation. The responses of Testskin cultures to acids and alkalis help to prove the concept that a topical application model can measure responses to these materials. These results suggest that human skin cell models can provide useful systems for preclinical skin irritation assessments, as alternatives to rabbits, for at least certain classes of test substances.

Use of human skin cell cultures for the estimation of potential skin irritants

We have investigated the use of cell cultures derived from human skin (keratinocytes and fibroblasts) and of cultured SV40 transformed human keratinocytes (SVK14 cells) for in vitro screening for skin toxicity. To assess the cytotoxic effects of a number of surfactants the following cytotoxicity assays were performed: (1) changes in cell morphology and cell number in confluent cultures; (2) inhibition of cell proliferation; (3) modulation of interleukin-6 (IL-6) production. The data obtained in vitro were compared with the results of an in vivo study (Tupker et al. Contact Dermatitis 1989, 20, 108–114), in which visual scoring and measurement of transepidermal water loss were taken as measures of skin irritancy. The results of the morphological and proliferation studies in vitro indicated a similar ranking order in skin irritancy as that found in the in vivo study. Furthermore, IL-6 production by cultured skin cells was increased on administration of nearly all of the surfactants tested. For a number of surfactants the increase in IL-6 production occurred at much lower concentration than those necessary to induce cytotoxic effect, suggesting that monitoring the IL-6 production on administration of skin irritating agents could be used as a very sensitive test.

In vitro skin irritation testing with human skin cell cultures

Cultured human skin cells are a potentially useful model for skin irritancy testing. We have evaluated the effects of chemical irritants on human epidermal keratinocytes (NHEK) and on keratinocyte-dermal fibroblast (NHEK/DF) co-cultures. Cell viability in NHEK cultures, measured as incorporation of the vital dye neutral red (NR), was reduced in a dose-dependent manner in response to the chemical irritants tested. The half-maximal effective concentration (NR 50) values correlated with irritation scores in human patch tests with these materials. Certain materials were found to be incompatible with this test system. NHEK/DF cultures were treated with ten prototype surfactants, and were evaluated for cell viability (MTT incorporation), cytotoxicity (release of the enzymes lactate dehydrogenase and N-acetyl glucosaminidase), metabolism (glucose utilization), and inflammatory mediator (prostaglandin E 2) release. There was a close correlation of the dose-response characteristics for all the endpoints tested, and between the in vitro responses and human patch test scores for the surfactants tested. These results demonstrate the usefulness of human skin cell cultures and of cell viability, cytotoxicity, and inflammatory mediator release as endpoints, for the in vitro assessment of skin irritancy.

Skeletal growth factor is produced by human osteoblast-like cells in culture

Human bone cells isolated from femoral heads were cultured in BGJ b medium containing bovine serum albumin (100 μg/ml), insulin (1 μg/ml) and epidermal growth factor (10 ng/ml), and the conditioned medium collected. The medium was concentrated, chromatographed using HPLC gel filtration (TSK 2000 SW), and assayed for mitogenic activity using [ 3H]thymidine incorporation into embryonic chick calvarial cells. The conditioned medium contained mitogenic activity which eluted with a different elution time than insulin or epidermal growth factor. Characterization of this activity suggests that it was due to human skeletal growth factor (SGF), a mitogen which had been previously isolated from human bone matrix. Common properties include: (1) stimulation of DNA synthesis in cultured embryonic chick calvarial cells, (2) competition with human SGF for binding to anti-SGF antibodies, (3) elution from HPLC gel filtration as a large factor ( M r 100 000) under native conditions but as a small factor ( M r 10 000) under dissociative conditions (4 M guanidine HCl), (4) elution time on HPLC reverse-phase chromatography (small SGF), (5) inactivation by dithiothreitol, (6) stability to heat, acidic or alkaline conditions and (7) inactivation by trypsin and chymotrypsin. These observations provide evidence that human bone cells produce SGF. Conditioned medium from human skin cell cultures also contained mitogenic activity. However, the activity was less than that from bone cells and did not cross-react with the rat anti-SGF antibodies.

The Cytotoxic Activity of Rabbit Immune Globulin Prepared from Tissue Cultures of Human Skin and Whole Human Placenta

Summary The preparation of rabbit immune globulins from tissue cultures of human skin cells and whole human placenta is described. An assay of the cytopathogenic effect of the anti-skin immune globulin demonstrated a profound activity against human cells of ectodermal and mesodermal origin. No effect on mouse liver epithelium and mouse subcutaneous (strain L) cells was found. A selective cytotoxicity was demonstrated by the anti-placental immune globulin in vitro. Only fibroblast-like cells were destroyed in cultures of mixed cells arising from skin. The cytotoxic activity of anti-skin globulin could be effectively inhibited by the presence of chicken plasma or pooled, frozen, human serum.