Antibody response to xenogeneic proteins in burned patients receiving cultured keratinocyte grafts

Production of Tissue-Engineered Skin Substitutes for Clinical Applications: Elimination of Serum

Tissue-engineered skin substitutes (TESs) are used as a treatment for severe burn injuries. Their production requires culturing both keratinocytes and fibroblasts. The methods to grow these cells have evolved over the years, but bovine serum is still commonly used in the culture medium. Because of the drawbacks associated with the use of serum, it would be advantageous to use serum-free media for the production of TESs. In a previous study, we developed a serum-free medium (Surge SFM) for the culture of keratinocytes. Herein, we tested the use of this medium, together with a commercially available serum-free medium for fibroblasts (Prime XV), to produce serum-free TESs. Our results show that serum-free TESs are macroscopically and histologically similar to skin substitutes produced with conventional serum-containing media. TESs produced with either culture media expressed keratin 14, Ki-67, transglutaminase 1, filaggrin, type I and IV collagen, and fibronectin comparably. Mechanical properties, such as contraction and tensile strength, were comparable between TESs cultured with and without serum. Serum-free TESs were also successfully grafted onto athymic mice for a six-month period. In conclusion, Surge SFM and Prime XV serum-free media could be used to produce high quality clinical-grade skin substitutes.

Hair Follicle Dermal Cells Support Expansion of Murine and Human Embryonic and Induced Pluripotent Stem Cells and Promote Haematopoiesis in Mouse Cultures

In the hair follicle, the dermal papilla (DP) and dermal sheath (DS) support and maintain proliferation and differentiation of the epithelial stem cells that produce the hair fibre. In view of their regulatory properties, in this study, we investigated the interaction between hair follicle dermal cells (DP and DS) and embryonic stem cells (ESCs); induced pluripotent stem cells (iPSCs); and haematopoietic stem cells. We found that coculture of follicular dermal cells with ESCs or iPSCs supported their prolonged maintenance in an apparently undifferentiated state as established by differentiation assays, immunocytochemistry, and RT-PCR for markers of undifferentiated ESCs. We further showed that cytokines that are involved in ESC support are also expressed by cultured follicle dermal cells, providing a possible explanation for maintenance of ES cell stemness in cocultures. The same cytokines were expressed within follicles in situ in a pattern more consistent with a role in follicle growth activities than stem cell maintenance. Finally, we show that cultured mouse follicle dermal cells provide good stromal support for haematopoiesis in an established coculture model. Human follicular dermal cells represent an accessible and readily propagated source of feeder cells for pluripotent and haematopoietic cells and have potential for use in clinical applications.

Synergistic Effects of FGF-2 with Insulin or IGF-I on the Proliferation of Human Auricular Chondrocytes

Chondrocyte preparation with the safety and efficiency is the first step in cartilage regenerative medicine. To prepare a chondrocyte proliferation medium that does not contain fetal bovine serum (FBS) and that provides more than a 1000-fold increase in cell numbers within approximately 1 month, we attempted to use the medium containing 5% human serum (HS), but it exerted no more than twofold increase in 2 weeks. To compensate for the limited proliferation ability in HS, we investigated the combinational effects of 12 factors [i.e., fibroblast growth factor(FGF)-2, insulin-like growth factor(IGF)-I, insulin, bone morphogenetic protein-2, parathyroid hormone, growth hormone, dexamethasone, 1α25-dihydroxy vitamin D3, L-3,3′,5′-triodothyronine, interleukine-1 receptor antagonist, 17β-estradiol, and testosterone] on the proliferation of human auricular chondrocytes by analysis of variance in fractional factorial design. As a result, FGF-2, dexamethasone, insulin, and IGF-I possessed promotional effects on proliferation, while the combination of FGF-2 with insulin or IGF-I synergistically enhanced the proliferation. Actually, the chondrocytes increased 7.5-fold in number in 2 weeks in a medium containing 5% HS with 10 ng/ml FGF-2, while the cell number synergistically gained a 10–12-fold increase with 5 μg/ml insulin or 100 ng/ml IGF-I in the same period. The proliferation effects were more enhanced at a concentration of 100 ng/ml for FGF-2, and especially for the combination of 100 ng/ml FGF-2 and 5 μg/ml insulin (approximately 16-fold within 2 weeks). In the long-term culture with repeated passaging, this combination provided more than 10,000-fold within 8 weeks (i.e., passage 4). Thus, we concluded that such a combination of FGF-2 with insulin or IGF-I may be useful for promotion of auricular chondrocyte proliferation in a clinical application for cartilage regeneration.

Culture of Keratinocytes for Transplantation without the Need of Feeder Layer Cells

Patients with large burn wounds have a limited amount of healthy donor skin. An alternative for the autologous skin graft is transplantation with autologous keratinocytes. Conventionally, the keratinocytes are cultured with mouse feeder layer cells in medium containing fetal calf serum (FCS) to obtain sufficient numbers of cells. These xenobiotic materials can be a potential risk for the patient. The aim of the present study was to investigate if keratinocytes could be expanded in culture without the need of a feeder layer and FCS. Keratinocytes were cultured on tissue culture plastic with or without collagen type IV coating in medium containing Ultroser G (serum substitute) and keratinocyte growth factor (KGF). An in vitro skin equivalent model was used to examine the capacity of these cells to form an epidermis. Keratinocytes in different passages (P2, P4, and P6) and freshly isolated cells were studied. Keratinocytes grown on collagen type IV were able to form an epidermis at higher passage numbers than cells grown in the absence of collagen type IV (P4 and P2, respectively). In both cases the reconstructed epidermis showed an increased expression of Ki-67, SKALP, involucrin, and keratin 17 compared to normal skin. Only 50,000 keratinocytes grown on collagen type IV in P4 were needed to form 1 cm2 epidermis, whereas 150,000 of freshly isolated keratinocytes were necessary. Using this culture technique sufficient numbers of keratinocytes, isolated from 1 cm2 skin, were obtained to cover 400 cm2 of wound surface in 2 weeks. The results show that keratinocytes can be cultured without the need of a fibroblast feeder layer and FCS and that these cells are still able to create a fully differentiated epidermis. This culture technique can be a valuable tool for the treatment of burn wounds and further development of tissue engineered skin.

Repeated intra-articular injection of allogeneic mesenchymal stem cells causes an adverse response compared to autologous cells in the equine model

Background

Intra-articular injection of mesenchymal stem cells (MSCs) is efficacious in osteoarthritis therapy. A direct comparison of the response of the synovial joint to intra-articular injection of autologous versus allogeneic MSCs has not been performed. The objective of this study was to assess the clinical response to repeated intra-articular injection of allogeneic versus autologous MSCs prepared in a way to minimize xeno-contaminants in a large animal model.

Methods

Intra-articular injections of bone marrow-derived, culture-expanded MSCs to a forelimb metacarpophalangeal joint were performed at week 0 and week 4 (six autologous; six autologous with xeno-contamination; six allogeneic). In the week following each injection, clinical and synovial cytology evaluations were performed.

Results

Following the first intra-articular injection, there were no differences in clinical parameters over time. Following the second intra-articular injection, there was a significant adverse response of the joint to allogeneic MSCs and autologous MSCs with xeno-contamination with elevated synovial total nucleated cell counts. There was also significantly increased pain from joints injected with autologous MSCs with xeno-contamination.

Conclusions

Repeated intra-articular injection of allogeneic MSCs results in an adverse clinical response, suggesting there is immune recognition of allogeneic MSCs upon a second exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0503-8) contains supplementary material, which is available to authorized users.

Stem cells of the human cornea

INTRODUCTION

Blindness affects 50 million individuals worldwide; a significant proportion of them require a cell or tissue-based repair or replacement strategy to mend their damaged or diseased cornea. This review will focus on the epithelial stem cell (ESC) population of the cornea, where they reside, how they are identified and what alternative cells can be used as functional substitutes.

SOURCE OF DATA

Data for this review were collated after performing literature searches by inserting key words (cornea, limbal, stem cells (SCs), epithelium, stroma, and endothelium) into the search engine PubMed.

AREAS OF AGREEMENT

The prevailing notion is that corneal ESCs reside in an exclusive niche and their activation is dictated by niche-specific signals.

AREAS OF CONTROVERSY

Recent studies refute this hypothesis, as the central cornea of many animal species also possesses similar proliferative and clonogenic activity. The other area of controversy is in relation to the use of autologous and/or allogeneic cell therapies which are mostly contaminated with xenogeneic factors, potentially exposing the recipient to potentially harmful foreign infection.

GROWING POINTS

Due to the shortage of donor corneal biomaterial, alternative cellular sources are being sought, discovered and trialed.

AREAS TIMELY FOR DEVELOPING RESEARCH

With the exception of conjunctival and oral mucosal epithelium, no other cell type has been successfully used to treat patients with severe corneal epithelial defects. Embryonic and foetal SCs may have the greatest potential of all; however there are moral, legal, religious and scientific hurdles to overcome before they become routinely used in the clinic.

Islet isolation for clinical transplantation

Islet transplantation is emerging as a viable treatment option for selected patients with type 1 diabetes. Following the initial report in 2000 from Edmonton of insulin independence in seven out of seven consecutive recipients, there has been a huge expansion in clinical islet transplantation. The challenge we now face is the apparent decline in graft function over time. Isolating high-quality human islets which survive and function for a longer period will no doubt contribute to further improvement in long-term clinical outcome. This chapter reviews the selection of appropriate donors for islet isolation and transplantation, describes each step during islet isolation, and discusses the scope for further improvements.

Development of an ex vivo human skin model for intradermal vaccination: tissue viability and Langerhans cell behaviour

The presence of resident Langerhans cells (LCs) in the epidermis makes the skin an attractive target for DNA vaccination. However, reliable animal models for cutaneous vaccination studies are limited. We demonstrate an ex vivo human skin model for cutaneous DNA vaccination which can potentially bridge the gap between pre-clinical in vivo animal models and clinical studies. Cutaneous transgene expression was utilised to demonstrate epidermal tissue viability in culture. LC response to the culture environment was monitored by immunohistochemistry. Full-thickness and split-thickness skin remained genetically viable in culture for at least 72 h in both phosphate-buffered saline (PBS) and full organ culture medium (OCM). The epidermis of explants cultured in OCM remained morphologically intact throughout the culture duration. LCs in full-thickness skin exhibited a delayed response (reduction in cell number and increase in cell size) to the culture conditions compared with split-thickness skin, whose response was immediate. In conclusion, excised human skin can be cultured for a minimum of 72 h for analysis of gene expression and immune cell activation. However, the use of split-thickness skin for vaccine formulation studies may not be appropriate because of the nature of the activation. Full-thickness skin explants are a more suitable model to assess cutaneous vaccination ex vivo.

A contact lens-based technique for expansion and transplantation of autologous epithelial progenitors for ocular surface reconstruction

BACKGROUND

A healthy cornea is reliant on a distinct population of stem cells (SC) that replace damaged or aging epithelium throughout life. Depletion of the SC pool or damage to the niche can result in a blinding and painful condition known as limbal-SC deficiency (LSCD). Although current treatment strategies for reconstituting the ocular surface for patients suffering LSCD are promising, they are complicated by transferring autologous or allogeneic progenitors in the presence of animal, human, and synthetic products. We report on the safe and efficacy of a unique autologous SC transfer technique that utilizes an Food and Drug Administration-approved contact lens (CL) as the SC substrate and carrier for patients with LSCD.

METHODS

Three patients with LSCD due to aniridia (n=1) and posttreatment for recurrent ocular surface melanoma (n=2) were included. Limbal (n=2) or conjunctival biopsies (n=1) were harvested and progenitors expanded ex vivo on therapeutic CLs in the presence of autologous serum. Cell-laden CLs were transferred to the patient's corneal surface and clinical outcome measures were recorded (follow-up range, 8-13 months).

RESULTS

A stable transparent corneal epithelium was restored in each patient. There was no recurrence of conjunctivalization or corneal vascularization, and a significant improvement in symptom score occurred in all patients. Best-corrected visual acuity was increased in all eyes after the procedure.

CONCLUSION

Ex vivo expansion of ocular surface epithelium in the presence of autologous serum and transplantation with the aid of a soft CLs is a promising new technique capable of achieving ocular surface rehabilitation.

Creating a spectrum of fibrocartilages through different cell sources and biochemical stimuli

In this study a scaffoldless approach was employed with two different cell sources and biochemical stimuli to engineer a spectrum of fibrocartilages representative of the different regions of the knee meniscus. Constructs composed of 100% fibrochondrocytes (FC) or a 50:50 co-culture of fibrochondrocytes and chondrocytes (CC) were cultured in 10% fetal bovine serum medium or serum-free "chondrogenic" medium, each +/-10 ng/mL TGF-beta1 (+T). Constructs from these two cell groups and four culture conditions were cultured for 6 weeks. By varying the cell type and presence of the growth factor, GAG per dry weight of the constructs spanned that of native tissue, ranging 16-45% and 1-7% in the CC and FC groups, respectively. Collagen density was most dependent on cell type and was significantly lower than tissue values. The collagen I/II ratio could be manipulated by cell type and serum presence to span the native range, from 3.5 in the serum-free CC group to over 1,000 in the FC groups treated with serum-containing medium. Using the CC cell group in the presence of serum-free medium dramatically increased the compressive stiffness to 128 +/- 34 kPa, similar to native tissue. Similarly, serum-free medium or TGF-beta1 treatment enhanced the tensile modulus by an order of magnitude, up to 3,000 kPa. Using two cell sources and manipulating biochemical stimuli, a range of fibrocartilaginous neotissues was engineered. Fibrocartilages such as the knee meniscus are characterized by heterogeneity in matrix and functional properties, and this work demonstrates a strategy for recreating these heterogeneous tissues.

Tissue engineered cartilage: utilization of autologous serum and serum-free media for chondrocyte culture

BACKGROUND

Standard culture medium contains bovine serum. If standard culture methodology is used for future human tissue-engineering, unknown risks of infection from bovine disease or immune reaction to foreign proteins theoretically might occur. In this study we wished to evaluate the potential of chondrocyte expansion using autologous and serum free media.

METHODS

Autologous auricular cartilage was harvested in a swine model. An initial concentration of 100x10(3) cells per group were expanded in three groups. Group A, F-12 with 10% fetal calf serum; Group B, F-12 supplemented with 10% autologous serum; Group C, F-12 supplemented with growth factors. Cell numbers were counted at days 3, 6, 9 and 12.

RESULTS

The cells in all the three groups exhibited normal chondrocyte morphology. At early time points there was a statistically significant difference in the number of cells between Group A and the two other groups (p<0.05). By day 12, both Groups A and C demonstrated greater cell number as compared to Group B (p<0.05).

CONCLUSION

The results suggest that both autologous serum as well as serum free media might be substituted for the expansion of the number of chondrocytes, thus avoiding the potential need for a bovine serum supplement.

Cartilage tissue engineering using human auricular chondrocytes embedded in different hydrogel materials

To seek a suitable scaffold for cartilage tissue engineering, we compared various hydrogel materials originating from animals, plants, or synthetic peptides. Human auricular chondrocytes were embedded in atelopeptide collagen, alginate, or PuraMatrix, all of which are or will soon be clinically available. The chondrocytes in the atelopeptide collagen proliferated well, while the others showed no proliferation. A high-cell density culture within each hydrogel enhanced the expression of collagen type II mRNA, when compared with that without hydrogel. By stimulation with insulin and BMP-2, collagen type II and glycosaminoglycan were significantly accumulated within all hydrogels. Chondrocytes in the atelopeptide collagen showed high expression of beta1 integrin, seemingly promoting cell-matrix signaling. The N-cadherin expression was inhibited in the alginate, implying that decrease in cell-to-cell contacts may maintain chondrocyte activity. The matrix synthesis in PuraMatrix was less than that in others, while its Young's modulus was the lowest, suggesting a weakness in gelling ability and storage of cells and matrices. Considering biological effects and clinical availability, atelopeptide collagen may be accessible for clinical use. However, because synthetic peptides can control the risk of disease transmission and immunoreactivities, some improvement in gelling ability would provide a more useful hydrogel for ideal cartilage regeneration.

Ex vivo development of a composite human oral mucosal equivalent

PURPOSE

The aim of this study was the ex vivo development of a composite oral mucosal equivalent composed of a continuous stratified layer of human oral keratinocytes grown on a cadaveric human dermal matrix in a defined medium without a feeder layer.

MATERIALS AND METHODS

Enzymatically dissociated human oral keratinocytes from keratinized oral mucosa were cultured, submerged in a serum-free, low-calcium (0.15 mmol/L) supplemented medium, and expanded through several passages. Once a sufficient population of keratinocytes was reached, they were seeded on 1-cm2 pieces of AlloDerm (LifeCell Co, Woodlands, TX), an acellular nonimmunogenic cadaveric human dermis, at cell densities of 2.5 X 10(4), 5.0 X 10(4), 1.25 X 10(5), or 2.5 X 10(5). The oral keratinocyte-AlloDerm composites were cultured while submerged in a high-calcium (1.8 mmol/L) medium for 4 days. After 4 days, the composites were raised to an air-liquid interface. Samples of the composites were taken for histologic examination at 4, 11, and 18 days postseeding of the keratinocytes on the AlloDerm.

RESULTS

At day 4, only the seeded cell density of 2.5 X 10(5) cells/cm2 formed a continuous monolayer on the AlloDerm. At day 11, a continuous stratified epithelium was seen, and at day 18 a well-differentiated, confluent parakeratotic epithelial layer was developed at cell densities of 5.0 X 10(4), 1.25 X 10(5), and 2.5 X 10(5)cells/cm2.

CONCLUSION

With the method used, it was possible to successfully develop an ex vivo composite oral mucosal equivalent that consisted of a stratified epidermis on a dermal matrix.

[Modifications in cultivating gingival keratinocytes]

Gingival keratinocyte grafts are usually cultured using 3T3 mouse fibroblasts as feeder cells and fetal calf serum as growth factor. These additives entail risks due to xenogenic DNA and protein. Therefore the explant and the disperse culture technique free of feeder cells were compared, and autogenous human serum was tested. Twelve halved gingival biopsies were trypsinized and cultured as single-cell suspensions, the other halves were cultured as explants. Six halved biopsies were cultured in autogenous serum, the other halves in fetal calf serum. Growth, morphology and cell biological aspects were compared. The single-cell suspensions did not form a confluent epithelial layer, whereas all explants formed confluent primary gingival keratinocyte cultures. The keratinocytes' growth in autogenous serum was equivalent to that in fetal calf serum. Morphology and cytokeratin expression were identical. The explant technique combined with autogenous serum can be used for culturing gingival autografts as well as for individual cultures for special issues.

Allogeneic fibroblasts used to grow cultured epidermal autografts persist in vivo and sensitize the graft recipient for accelerated second-set rejection

INTRODUCTION

Cultured epidermal autografts (CEAs) have been used for wound coverage in patients with massive burns and other skin defects. However, CEAs often display late breakdown, which may be immunologically mediated and initiated by persistent foreign fibroblasts used as a feeder layer to optimize keratinocyte growth. This study investigates whether these fibroblasts, previously shown to persist in vitro, survive after grafting and induce host sensitization to alloantigen.

METHODS

CEAs from CBA donors (H-2k) were grown on allogeneic NIH 3T3 (H-2q) or syngeneic LTK (H-2k) fibroblasts, which were removed by trypsinization 7 days later. CBA mice (n = 85) were flank-grafted with NIH allografts (positive control), CEA/3T3s, CEA/LTKs, or CBA autografts (negative control). Hosts were challenged with second set NIH tail allografts 3 weeks later. Median graft survival was compared between groups by Wilcoxon rank and chi 2 analysis. Additional CBA mice (n = 15) received CEAs that were biopsied 0, 4, and 8 days after grafting. The presence of allogeneic fibroblasts was determined by Western immunoblotting, using KL295, a monoclonal antibody that recognizes H-2q (but not H-2k) class II histocompatibility antigens.

RESULTS

Allogeneic fibroblasts persisted after grafting but decreased over time, as determined by alloantigen expression on Western immunoblots. Accelerated tail graft rejection occurred in hosts primed by NIH allografts (9 days, p < 0.05), as well as by CEAs growth with an allogeneic (10 days, p < 0.05) but not a syngeneic feeder layer (12 days, NS). Mice receiving flank autografts rejected second set tail allografts at 12 days.

CONCLUSIONS

Immunogenic fibroblasts used to grow CEAs survive in vivo and sensitize the graft recipient for accelerated second-set rejection. These persistent cells may initiate an inflammatory response that may result in late graft breakdown and limit the utility of CEAs grown with a foreign fibroblast feeder layer.

Xenogeneic mouse fibroblasts persist in human cultured epidermal grafts: a possible mechanism of graft loss

Recent reports suggest that long-term graft take of cultured epidermal autografts (CEAs) is less than 50% when late graft loss is considered. The characteristics of late CEA loss suggest that it may occur as a result of an immunologic reaction to persistent xenogeneic cells and/or proteins used to grow CEA. In this study we examined whether immunologically reactive, mouse 3T3 fibroblasts used as feeder layers can persist in primary, secondary, and tertiary human CEA. We cocultured keratinocytes from 11 separate burn patients with growth-arrested 3T3 fibroblasts. After removing visible 3T3 fibroblasts from CEA with trypsinization, we allowed CEA to reach confluence. We then harvested CEA either as primary, secondary, or tertiary cultures. We detected mouse fibroblasts using fluorescence activated cell sorting (FACS) with a monoclonal antibody specific for mouse major histocompatibility (MHC) antigens. We detected mouse MHC class II antigens by performing Western immunoblotting with another mouse MHC-specific monoclonal antibody. By FACS we identified mouse fibroblasts in 100, 75, and 62.5% of primary, secondary, and tertiary passage CEAs, respectively. Similarly by immunoblotting we found mouse MHC class II antigen in 100, 80, and 66.7% of primary, secondary, and tertiary CEAs. These results demonstrate that xenogeneic fibroblast feeder layers capable of generating immunogenic transplantation antigens persist in CEAs. The persistence of these cells and their antigen expression may contribute to CEA loss.

Functional innervation of cultured skin grafts

The aims of the present study were to determine 1) if grafts of cultured skin become innervated; and 2) whether tactile function of these grafts could be improved by implanting target tissue into them. Autologous skin equivalents were generated in vitro (30 d) for individual adult Sprague-Dawley rats. Some animals received pure skin equivalent grafts; others had target tissue consisting of 2-mm punch biopsies (normal skin or touch domes) inserted into their skin equivalents at the time of grafting. After 83 d, physiologic recordings were obtained from afferent nerves innervating the grafts. Tissue was processed for histology at various intervals. Silver staining of the tissues demonstrated many isolated nerve fibers in the dermis of cultured areas of skin as well as in implant zones. When grafts were rubbed with a glass rod or pinched with watchmaker forceps, impulses were evoked in nerves innervating both implant and cultured regions. In contrast, the afferent response to gently stroking grafts with a camel hair brush was severely reduced in cultured areas but was vigorous in implanted skin. Neuronal activity characteristic of type I neurons innervating touch domes was only found in cutaneous nerves innervating implants originally possessing domal tissue. Furthermore, grafts with good takes had better return of sensory function than grafts undergoing episodes of crusting. These results suggest that structural components or trophic factors present in implants enhanced the return of neural function related to the sensory modality of light touch; and this was also affected by the engraftment quality.

Tactile function in skin-equivalent grafts

Cultured grafts are excellent wound covers; however, their somatosensory capabilities are unknown. This is a preliminary report of a study which determined whether grafts of cultured skin become innervated and also examined whether seeding grafts with target tissue improved nerve growth or functional recovery. Autologous skin for grafting was generated from adult rat biopsy tissue. Dissociated keratinocytes were seeded on top of fibroblast-contracted collagen gels (skin-equivalents). Some animals received grafts composed entirely of skin-equivalents. Others had grafts with 2-mm punch biopsies (normal skin or touch domes) inserted into them. Prior to sacrifice, whole nerve recordings of the cutaneous nerves supplying the grafts were made following tactile mechanical stimulation of the graft surfaces. Tissue was processed for light and electron microscopy as well as silver stained. Nerve fibers were present in the dermis (generated from the fibroblast contracted collagen gels) of all animals and often extended to the epidermis. Light brushing of the cultured areas of the grafts produced little or no activity in the cutaneous nerves; however, afferent impulses were generated after rubbing the skin with a glass rod or pinching it with fine forceps. The implanted regions within the skin-equivalents varied from this pattern. Lightly brushing their surface resulted in vigorous activity in the nerves. Elements in the skin therefore seemed to enhance nerve regeneration and function. However, the quality of the engraftment was also important. Implanted regions of grafts experiencing poor "takes" had compromised innervation.

Skin replacement using collagen extracted from bovine hide

This paper reviews the use of biological sponge-shape matrices as dermal replacements in order to orient newly formed wound tissue. Sponge-shape matrices consist of a scaffold made of cross-linked collagen extracted from bovine hide. Other molecules with specific activities on wound tissue ingrowth are bound to collagen. The lamination of sponge with a synthetic material allows this device to be implanted as a temporary skin substitute. For the epidermal cell layer replacement, a biological film-shape matrix can be used in order to cultivate autologous cells during the period that biological sponge-shape matrices are invaded by wound tissue.