Biomedical subjects

N L Parenteau

Publications and source records attributed to N L Parenteau.

11 recordsLinked to original sources

PubMed1999

The allogeneic response to cultured human skin equivalent in the hu-PBL-SCID mouse model of skin rejection.

BACKGROUND: Engineered tissues have been proposed for the treatment of a variety of conditions including the partial or complete replacement of human organs. To determine the basis for the rejection of these tissues, we analyzed the immune response to allogeneic human skin equivalent (HSE, also called Apligraf) in the humanized SCID mouse (hu-PBL-SCID). METHODS: Two models of hu-PBL-SCID were used for these studies. In one model, human skin or HSE was transplanted onto humanized mice so that graft survival could be analyzed. In the other model, skin grafts were allowed to heal on naive mice before humanization. This model was used to analyze the immunologic response to the vascularized skin allograft. Humanization was performed by adoptive transfer of human PBL into SCID mice by i.p. injection. RESULTS: Both human foreskin and HSE successfully engrafted onto naive SCID mice and remained stable for more than 6 months. In contrast, human foreskin was rejected by 21 days posttransplant in hu-PBL-SCID, whereas HSE consistently engrafted for more than 28 days. Treatment of HSE grafts with interferon-y for 5 days to induce maximal MHC class II molecule expression before grafting failed to induce rejection. HSE also engrafted onto hu-PBL-SCID mice that were exposed to alloantigen by prior injection with interferon-gamma-treated keratinocytes identical to those used to generate the HSE. In addition, we determined that humanization of SCID mice following engraftment and vascularization of human foreskin resulted in marked CD3+ T cell infiltrates and a lymphocyte-induced vasculitis. In contrast, the response in vascularized HSE was associated with minimal CD3+ T cell infiltration in the absence of vasculitis or morphological features of rejection. CONCLUSION: These results support the use of HSE and other allogeneic engineered tissues in humans provided that such tissues are limited in their antigen presenting capabilities. In addition, our findings suggest a critical function for the donor endothelial cell in rejection.

Animals↗

PubMed1996

Cultured skin as a 'smart material' for healing wounds: experience in venous ulcers.

The healing of chronic wounds is a difficult and varied problem. The engineering of a cultured skin tissue offers an adaptive therapy for chronic wounds. Our hypothesis has been that living tissue can act as a 'smart material' to heal wounds. We have examined the healing characteristics of a bilayered cultured skin equivalent (Graftskin) in a controlled study and present clinical data from interim analyses for 233 patients over 6 months of treatment. All venous ulcer patients will be followed for up to 1 year. We report on three basic scenarios of healing: (i) promotion of healing by secondary intention, (ii) persistent biological wound closure with stimulation of underlying healing, and (iii) healing by frank graft take of the cultured material with remodelling of the tissue over time. Our results indicate that the cultured skin equivalent is responsive to individual wound conditions and thus acts as a 'smart material' in the chronic wound.

Adult↗

PubMed1994

Basement membrane assembly and differentiation of cultured corneal cells: importance of culture environment and endothelial cell interaction.

A three-dimensional corneal tissue construct was used to examine the effect of culture environment and endothelial cell interaction on epithelial differentiation and basement membrane assembly. Rabbit corneal epithelial cells were cultured over rabbit stromal fibroblasts in a collagen matrix with or without an underlying layer of immortalized mouse corneal endothelial cells (Muragaki, Shiota, Inoue, Ooshima, Olsen, and Ninomiya. (1992) Eur. J. Biochem. 207, 895-902). The cultures were grown submerged or at a dry or moist interface. Basement membrane, anchoring fibril, and hemidesmosome assembly was monitored using transmission electron microscopy as well as indirect immunofluorescence microscopy of laminin, type VII collagen, and alpha 6 integrin. Antibodies against keratin 3 (K3) and alpha-enolase marked differentiated and undifferentiated corneal epithelial cells, respectively. When all three cell types were cultured at a moist interface, hemidesmosomes, anchoring fibrils, and a continuous basement membrane were observed 2 wk after lifting the cultures to an air-liquid interface (air-lift). The distribution of alpha-enolase and K3 was identical to patterns seen in the limbal region of the cornea. Air-lifted tissue constructs lacking the endothelial cell layer showed only limited distribution of laminin and type VII collagen at the epithelial-matrix junction. alpha 6 Integrin was present along the entire plasma membrane of the basal cells; epithelial differentiation was not complete as alpha-enolase was seen in basal and two to three layers of suprabasal cells. Submerged cultures without endothelial cells did not express differentiation markers or basement membrane components. These data indicate that endothelial cell interaction dramatically enhances the amount and quality of epithelial basement membrane assembly and that epithelial differentiation is influenced by the type of interface between tissue, liquid, and air.

Animals↗

PubMed1993

Development of a stratum corneum and barrier function in an organotypic skin culture.

The stratum corneum of human skin is responsible for maintaining the epidermal permeability barrier. We have developed a bilayered skin culture (SC) which forms a corneum 35 +/- 1 cell layers thick 21 days after being raised to the air-liquid (A/L) interface. By the 7th day after raising to the A/L interface the corneocytes were irregularly shaped and had cross-sectional areas (CSA) of > or = 300 microns 2. By the 21st day the corneocytes had assumed polygonal shapes and had a CSA (100-250 microns 2) similar to that of human foreskin. The total lipid (TL) content of the corneum averaged 5-7% of the lyophilized weight. Ceramide content increased from 20% of TL at day 7 of A/L interface culture to 30% at day 21. Triglycerides decreased from 43% to 17% of TL during the same period. Free fatty acids comprised 5.5% of TL at day 21 of A/L interface culture. The intercorneocyte spaces contained stacks of lipid lamellae. However, the stacks lacked the Landmann unit repeat. Abnormal lamellar structures were observed in both the intra- and extracorneocyte spaces. Transepidermal water loss (TEWL) was > 4 mg/cm2 per h throughout the culture period. Lipid supplementation of the culture medium and culturing in a low humidity environment improved barrier function by 50%. However, the effects were not additive. The SC developed a near-normal corneum, but did not achieve barrier competence, due at least partially to abnormalities in lipid composition and organization.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Water↗

PubMed1992

The organotypic culture of human skin keratinocytes and fibroblasts to achieve form and function.

We describe an organotypic model of human skin comprised of a stratified layer of human epidermal keratinocytes and dermal fibroblasts within a contracted collagen lattice. Feasible and reproducible production of the skin construct has required the use of traditional as well as specialized culture techniques. The configuration of the construct has been engineered to maintain polarity and permit extended culture at the air-liquid interface. Morphological, biochemical and kinetic parameters were assessed and functional assays were performed to determine the degree of similarity to human skin. Light and ultrastructural morphology of the epidermis closely resembled human skin. The immunocytochemical localization of a number of differentiation markers and extracellular matrix proteins was also similar to human skin. Kinetic data showed a transition of the epidermal layer to a more in vivo-like growth rate during the development of the construct at the air-liquid interface. The barrier properties of the construct also increased with time reaching a permeability to water of less than 2%-h after approximately 2 weeks at the air-liquid interface which is still on average 30-fold more water-permeable than normal human skin. The construct is currently used for in vitro research and testing and is also being tested in clinical applications.

Biological Dressings↗

PubMed1992

Serial cultivation of normal human keratinocytes: a defined system for studying the regulation of growth and differentiation.

We have developed a defined method for human epidermal keratinocyte culture. The minimally supplemented basal medium supported establishment of primary cultures from neonatal foreskin in a defined environment. It also supported serial cultivation and rapid expansion of cell number. Casein replaced serum for defined cryopreservation. Cells were serially cultivated in medium containing 0.08 mM calcium. The rate of cell division however remained high after addition of 1.8 mM calcium. The particulate transglutaminase activity of the cultures was low at confluence, even in the presence of 1.88 mM calcium, indicating an enrichment of the basal cell population. Culture with small amounts (0.3%) of chelated serum increased particulate transglutaminase activity approximately 2.2-fold in low calcium cultures and approximately 3.5-fold in high calcium cultures. A gradual reduction in growth rate of serum-treated cultures upon serial cultivation also indicated a depletion of cells with basal cell character. Bovine hypothalamic extract and cholera toxin were able to avert, in part, the differentiation-promoting effects of serum. Keratinocytes serially cultivated in the defined medium maintained the ability to develop normally into a morphologically differentiated epidermis.

Blood Proteins↗

PubMed1992

Keratinocyte transglutaminase: differentiation marker and member of an extended family.

Transglutaminases stabilize a variety of biological structures by cross-linking constituent proteins. This action appears physiologically important in stabilizing (1) keratinocyte cornified envelopes, (2) fibrin clots, (3) the copulation plug in rodents, and (4) the fertilized egg surface in aquatic species. Several transglutaminases that participate in such processes have been well characterized and found, though highly divergent, to differ in sequence primarily at the amino terminus. Comparison of their gene structures suggests a likely mechanism by which new members may arise that assume a diversity of functions. The functions of some members of this family are presently unknown, including the tissue transglutaminase found in many mammalian cell types, and those found in plants. Most of the transglutaminases identified are soluble enzymes, but several that are membrane-bound have gained recognition recently. The best characterized of the latter is keratinocyte transglutaminase, which is anchored in the membrane by acylated fatty acid. Important for proper epidermal cell maturation, expression of this enzyme is greatly altered by physiological effectors and toxic agents. In addition, it is induced by cultivation of cells from non-squamous epithelia. Thus, it is a promising marker for helping to elucidate the molecular basis by which keratinocyte differentiation is elicited or altered.

Amino Acid Sequence↗

PubMed1991

Epidermis generated in vitro: practical considerations and applications.

The technology for culture of epidermis is one of the most advanced to date for generation of a tissue in vitro. Cultured epidermis is already used for a number of applications ranging from use as a permanent skin replacement to use as an organotypic culture model for toxicity testing and basic research. While simple epidermal sheets have been grafted successfully, more advanced models for skin replacement consisting of both dermal and epidermal components are in development and being tested in a number of laboratories. One of the most advanced in vitro models is the living skin equivalent, an organotypic model consisting of a collagen lattice contracted and nourished by dermal fibroblasts overlaid with a fully formed epidermis.

Culture Techniques↗

PubMed1989

Coordination of keratinocyte programming in human SCC-13 squamous carcinoma and normal epidermal cells.

Exploiting the sensitivity of neoplastic keratinocytes to physiological effectors, this work analyzes the degree of coordination among differentiation markers in the established human epidermal squamous carcinoma cell line SCC-13 in comparison to normal human epidermal cells. This analysis showed that overall keratin content was modulated substantially and in parallel with particulate transglutaminase activity in response to variation of calcium, retinoic acid, and hydrocortisone concentrations in the medium. The changes in keratin expression were evident primarily in the striking stimulation by hydrocortisone or calcium and the virtual suppression by retinoic acid of species in the 56-58 kd region, which have not previously been reported subject to such physiological modulation. In contrast, involucrin levels were coordinated only to a limited degree with particulate transglutaminase activity and keratin content. The very low involucrin levels observed in low calcium medium were increased 5- to 10-fold in high calcium medium. However, they were also increased 5- to 30-fold in low calcium medium by retinoic acid, a clear example of uncoupling. Activities of the tissue transglutaminase were altered considerably by the various culture conditions but were not obviously coordinated to keratinocyte markers. In normal epidermal cells, the suppressive effect of retinoic acid was much more evident with particulate transglutaminase than involucrin levels. While calcium had a large stimulatory effect on both markers, hydrocortisone had little or no influence. These results emphasize the potential importance of quantitative analysis of differentiation markers for resolving the contribution of physiological elements in coordination of cellular programming.

Calcium↗

PubMed1987

Primate involucrins: antigenic relatedness and detection of multiple forms.

Hominoid apes (gorilla, chimpanzee, orangutan, gibbon), Old World monkeys (rhesus, cynomolgus), New World monkeys (owl, cebus), and a prosimian (lemur) express involucrin-like proteins in cultured keratinocytes. Primate involucrins can be precipitated with trichloroacetic acid, resolubilized at pH 8, and subsequently retain aqueous solubility in 67% ethanol. Polyacrylamide gel electrophoresis of keratinocyte extracts after this rapid partial purification has revealed in each species tested one (chimpanzee, orangutan, gibbon) or two (gorilla, rhesus, owl, cebus) antigenically crossreactive proteins that migrate in the vicinity of human involucrin. In the species examined further (gorilla, chimpanzee, rhesus), poly(A)+ mRNA isolated from the cultures directed the cell-free translation of polypeptides with mobilities similar to those extracted from the cells. From five cynomolgus monkeys, three different electrophoretic profiles were obtained, suggesting the existence of different alleles. Quantitative comparisons by a sensitive enzyme-linked immunosorbent assay indicated that certain primate involucrins have a higher density of antigenic determinants than the human protein, whereas others lack some determinant(s). In contrast to those from other species, all of which showed substantial crossreactivity, the lemur protein was minimally immunoreactive by immunoblotting and not clearly detected by solid-phase assay. The electrophoretic and antigenic differences displayed throughout the primate order suggest that this protein has been subject to relatively rapid evolution.

Animals↗

PubMed1986

Induction of keratinocyte type-I transglutaminase in epithelial cells of the rat.

Using immunogold-silver techniques, we have demonstrated that, in rats, type-I (keratinocyte) transglutaminase is expressed primarily in stratified squamous epithelia of the integument, the upper digestive tract, and the lower female genital tract. In these epithelia, the enzyme was found to be present predominantly in the granular layer, but was evident at low levels even in the basal layer, especially in the genital tract. No immunoreactivity was detected in glandular, columnar, or transitional epithelia or in soft tissues. However, considerable enzyme antigenicity was observed in the endometrium and in major ducts of the pancreas and mammary glands of near-term pregnant and early postpartum females. In cultures, substantial immunoreactivity was readily identifiable not only in epidermal, vaginal, and esophageal epithelial cells (immunopositive in vivo), but also in urinary bladder, seminal vesicle, and tracheal epithelial cells (immunonegative in vivo). Primary epithelial outgrowths from bladder and seminal vesicle tissue explants were immunopositive, demonstrating rapid adaptation to the culture environment. These results reveal three distinct levels of regulation of transglutaminase expression in various cell types: during the differentiation of keratinocytes, during pregnancy, being evident principally in the endometrium but detectable elsewhere as well, and during the cultivation of certain epithelia which do not normally express the enzyme in vivo. We conclude that type-I transglutaminase may be a valuable marker for elucidating the regulation of normal epithelial differentiation and squamous metaplasia.

Animals↗