Treatment of skin ulcers with cultured epidermal allografts

Vascularized 3D Human Skin Models in the Forefront of Dermatological Research

In vitro engineered skin models are emerging as an alternative platform to reduce and replace animal testing in dermatological research. Despite the progress made in recent years, considerable challenges still exist for the inclusion of diverse cell types within skin models. Blood vessels, in particular, are essential in maintaining tissue homeostasis and are one of many primary contributors to skin disease inception and progression. Substantial efforts in the past have allowed the successful fabrication of vascularized skin models that are currently utilized for disease modeling and drugs/cosmetics testing. This review first discusses the need for vascularization within tissue-engineered skin models, highlighting their role in skin grafting and disease pathophysiology. Second, the review spotlights the milestones and recent progress in the fabrication and utilization of vascularized skin models. Additionally, advances including the use of bioreactors, organ-on-a-chip devices, and organoid systems are briefly explored. Finally, the challenges and future outlook for vascularized skin models are addressed.

The Application of Adipose Tissue-Derived Mesenchymal Stem Cells (ADMSCs) and a Twin-Herb Formula to the Rodent Wound Healing Model: Use Alone or Together?

Our previous study reported that mesenchymal stem cells (MSCs) accelerated the wound healing process through anti-inflammatory, anti-apoptotic, and pro-angiogenetic effects in a rodent skin excision model. NF3 is a twin-herb formula, which presents similar effects in promoting wound healing. Research focusing on the interaction of MSCs and Chinese medicine is limited. In this study, we applied MSCs and the twin-herb formula to the wound healing model and investigated their interactions. Wound healing was improved in all treatment groups (MSCs only, NF3 only, and MSCs + NF3). The combined therapy further enhanced the effect: more GFP-labelled ADMSCs, collagen I and collagen III expression, Sox9 positive cells, and CD31 positive cells, along with less ED-1 positive cells, were detected; the expressions of proinflammatory cytokine IL-6 and TNF-α were downregulated; and the expression of anti-inflammatory cytokine IL-10 was upregulated. In vitro, NF3 promoted the cell viability and proliferation ability of MSCs, and a higher concentration of protein was detected in the NF3-treated supernatant. A proteomic analysis showed there were 15 and 22 proteins in the supernatants of normal ADMSCs and NF3-treated ADMSCs, respectively. After PCR validation, the expressions of 11 related genes were upregulated. The results of a western blot suggested that the TGFβ/Smad and Wnt pathways were related to the therapeutic effects of the combined treatment. Our study suggests for the first time that NF3 enhanced the therapeutic effect of MSCs in the wound healing model and the TGFβ/Smad and Wnt pathways were related to the procedure.

Laminin-511-derived recombinant fragment and Rho kinase inhibitor Y-27632 facilitate serial cultivation of keratinocytes differentiated from human embryonic stem cells

INTRODUCTION

Keratinocytes derived from pluripotent stem cells have a short proliferative lifespan under conventional culture conditions that are optimized for keratinocytes. Recently, a Rho kinase inhibitor, Y-27632, had been used as a standard supplement for culture medium in which the proliferative lifespan of postnatal keratinocytes was markedly expanded. In addition, recombinant human laminin-511 was demonstrated to be an adhesive ligand for promoting proliferation of cultured epidermal keratinocytes. Based on this knowledge, efficacies of Y-27632 and a laminin511-derived recombinant fragment, known as laminin-511 E8 fragment (LN-511-E8), were evaluated for establishing cultivation methods of keratinocyte differentiated from human embryonic stem cells (hESC).

METHODS

Differentiated cells from hESCs, which were established with clinical grade in previous study, were seeded onto culture dishes coated with LN-511-E8 and co-cultured with a mouse feeder layer in serum-free medium supplemented with Y-27632. Before serial cultivation, hESC-derived keratinocytes were separated from other differentiated cells by trypsinization. The isolated hESC-derived keratinocytes were used for evaluating clonogenicity, gene expression analysis for keratinocyte markers, potency of terminal differentiation by air-lifting culture, and long-term proliferation activity by serial cultivation. Moreover, efficacies of Y-27632, LN-511-E8, and mouse feeder layer were evaluated on proliferation of hESC-derived keratinocytes.

RESULTS

hESC-derived keratinocytes with activity of clonal growth were successfully isolated by trypsinization and exhibited potency of differentiation to form stratified epidermal equivalents with expressions of progenitor and differentiation markers of epidermal keratinocyte. Y-27632 and LN-511-E8 were required for maintaining the proliferative activity of the hESC-derived keratinocytes in serially cultivation using mouse feeder layer with stable doubling time during logarithmic growth phase.

CONCLUSIONS

These results indicate the utility of Y-27632 and LN-511-E8 for serial cultivation of hESC-derived keratinocytes, which have a potential for fabricating allogeneic cellular products in clinical situations for regeneration of stratified epithelial tissues.

Recent Advances in Modified Cellulose for Tissue Culture Applications

Tissue engineering is a rapidly advancing field in regenerative medicine, with much research directed towards the production of new biomaterial scaffolds with tailored properties to generate functional tissue for specific applications. Recently, principles of sustainability, eco-efficiency and green chemistry have begun to guide the development of a new generation of materials, such as cellulose, as an alternative to conventional polymers based on conversion of fossil carbon (e.g., oil) and finding technologies to reduce the use of animal and human derived biomolecules (e.g., foetal bovine serum). Much of this focus on cellulose is due to it possessing the necessary properties for tissue engineering scaffolds, including biocompatibility, and the relative ease with which its characteristics can be tuned through chemical modification to adjust mechanical properties and to introduce various surface modifications. In addition, the sustainability of producing and manufacturing materials from cellulose, as well as its modest cost, makes cellulose an economically viable feedstock. This review focusses specifically on the use of modified cellulose materials for tissue culturing applications. We will investigate recent techniques used to promote scaffold function through physical, biochemical and chemical scaffold modifications, and describe how these have been utilised to reduce reliance on the addition of matrix ligands such as foetal bovine serum.

Synthetic polymeric biomaterials for wound healing: a review

Wounds are of a variety of types and each category has its own distinctive healing requirements. This realization has spurred the development of a myriad of wound dressings, each with specific characteristics. It is unrealistic to expect a singular dressing to embrace all characteristics that would fulfill generic needs for wound healing. However, each dressing may approach the ideal requirements by deviating from the 'one size fits all approach', if it conforms strictly to the specifications of the wound and the patient. Indeed, a functional wound dressing should achieve healing of the wound with minimal time and cost expenditures. This article offers an insight into several different types of polymeric materials clinically used in wound dressings and the events taking place at cellular level, which aid the process of healing, while the biomaterial dressing interacts with the body tissue. Hence, the significance of using synthetic polymer films, foam dressings, hydrocolloids, alginate dressings, and hydrogels has been reviewed, and the properties of these materials that conform to wound-healing requirements have been explored. A special section on bioactive dressings and bioengineered skin substitutes that play an active part in healing process has been re-examined in this work.

A Concise Review on the Use of Mesenchymal Stem Cells in Cell Sheet-Based Tissue Engineering with Special Emphasis on Bone Tissue Regeneration

The integration of stem cell technology and cell sheet engineering improved the potential use of cell sheet products in regenerative medicine. This review will discuss the use of mesenchymal stem cells (MSCs) in cell sheet-based tissue engineering. Besides their adhesiveness to plastic surfaces and their extensive differentiation potential in vitro, MSCs are easily accessible, expandable in vitro with acceptable genomic stability, and few ethical issues. With all these advantages, they are extremely well suited for cell sheet-based tissue engineering. This review will focus on the use of MSC sheets in osteogenic tissue engineering. Potential application techniques with or without scaffolds and/or grafts will be discussed. Finally, the importance of osteogenic induction of these MSC sheets in orthopaedic applications will be demonstrated.

Proliferative activity of skeletal myoblast sheet by paracrine effects of mesenchymal stem cells

OBJECTIVES

The purpose of this study was to examine the proliferative activity enhancement of skeletal myoblasts in the presence and absence of mesenchymal stem cells (MSC).

METHODS

We artificially fabricated two types of cell sheets by co-culturing rabbit skeletal myoblast sheets with rabbit MSCs using type IA collagen gel (MC+), and cell sheets without rabbit MSCs (MC-).

RESULTS

The results of hematoxylin and eosin staining revealed that MC+ was thicker than MC- on day 7. Immunohistochemical staining revealed a low level of desmin expression in both sheets on day 2. Desmin expression increased at days 7 and 12, and desmin localization was consistent with the stratified area. Reverse transcription PCR revealed the presence of MyoD and PAX7 in both sheets on days 2, 7, and 12. The presence of myogenin was confirmed in both sheets on days 7 and 12. Hepatocyte growth factor expression was evident in MC+ on day 2, and in both sheets on day 7. Measurement of cell proliferative activity based on DNA cell cycle analysis indicated that MC+ had significantly higher cell proliferative activity than MC- on day 7. There were no significant differences in cell proliferative activity between MC+ and MC- on day 12.

CONCLUSIONS

This study demonstrated that the presence of MSCs could transiently enhance the proliferative activity of myoblasts, but that this enhancement is ultimately diminished due to contact inhibition.

Using Living Skin Equivalents for Diabetic Foot Ulceration

Diabetic foot ulcers are a major clinical challenge with enormous socioeconomic consequence. All advances in the understanding and management of this problem are eagerly received by wound specialists. The development of bioengineered skin—living skin equivalent—is an interesting event that could be significant in the management of lower extremity wounds such as the diabetic foot ulcer.

A Clinical Investigation on the Characteristics and Outcomes of Treating Chronic Lower Extremity Wounds using the TissueTech Autograft System

The application of tissue engineering technology to wound healing has resulted in the development of a number of “living skin equivalents.” These have become a viable option in the treatment of chronic, nonhealing wounds. Such wounds present a major cost burden as well as increased morbidity and mortality. Unique among skin tissue engineering technology is the TissueTech autograft system, as it incorporates an autologous dermal substitute—Hyalograft® 3D—and an autologous epidermal replacement, Laserskin® autograft. Each includes a matrix of a hyaluronic acid ester to promote cellular migration and graft take.

A Prospective Multicenter Study of the Efficacy and Tolerability of Cryopreserved Allogenic Human Keratinocytes to Treat Venous Leg Ulcers

Allogeneic human keratinocyte cultures have been used to treat burn wounds, donor sites, and chronic skin ulcers with some success. Cryopreservation of these cultures allows for the production of large standardized batches that are readily available for use. The aim of the study presented in this report was to study effects of cryopreserved cultured allogenic human keratinocytes (Cryo Ceal) on chronic lower extremity wounds. Parameters were measured to study efficacy, tolerability, pain associated with chronic wounds, and quality of life of patients. Twenty-seven patients with hard-to-heal venous leg ulcers received a maximum of 9 applications of Cryo Ceal in a prospective, uncontrolled multicenter study lasting 48 weeks. Eleven out of 27 patients (41%; 95% CI: 22%-61%) had complete wound closure within 24 weeks (1 week). The time required for complete wound closure in these 11 patients ranged from 4.1 to 24.9weeks. Only 1 patient had recurrence of the ulcer at 48 weeks. Local (wound) pain scores decreased from a mean of 2.5 at baseline to 0.9 at week 24. Fifty percent of the patients attained a pain score of 0 after 12 weeks and remained stable at this score until the end of the study. Overall, the patient quality of life was better at week 24, compared to baseline values. The treatment was well tolerated, and wound infection was the most frequently occurring adverse event.

Cutaneous Tissue Engineering and Lower Extremity Wounds (Part 1)

Tissue-engineered skin is a novel therapeutic with which difficult-to-heal lower extremity wounds may be treated. Such skins are products of cutaneous tissue engineering that provide an alternative for autologous or allogeneic tissue transplantation, thereby avoiding problems associated with donor site availability, the risk of infection, and scarring. Recently developed tissue-engineered skin equivalents have shown to be superior in certain ways to compression therapy for refractory venous ulcers and acute wounds. These biologic products behave similarly to autografts.

Scaffold and scaffold-free self-assembled systems in regenerative medicine

Self-assembly in tissue engineering refers to the spontaneous chemical or biological association of components to form a distinct functional construct, reminiscent of native tissue. Such self-assembled systems have been widely used to develop platforms for the delivery of therapeutic and/or bioactive molecules and various cell populations. Tissue morphology and functional characteristics have been recapitulated in several self-assembled constructs, designed to incorporate stimuli responsiveness and controlled architecture through spatial confinement or field manipulation. In parallel, owing to substantial functional properties, scaffold-free cell-assembled devices have aided in the development of functional neotissues for various clinical targets. Herein, we discuss recent advancements and future aspirations in scaffold and scaffold-free self-assembled devices for regenerative medicine purposes. Biotechnol. Bioeng. 2016;113: 1155-1163. © 2015 Wiley Periodicals, Inc.

Membrane-Permeable Calpain Inhibitors Promote Rat Oral Mucosal Epithelial Cell Proliferation by Inhibiting IL-1α Signaling

To standardise regenerative medicine using cultured cells, the use of serum-free, chemically defined media will be necessary. We have reported that IL-1α inhibits the growth of epithelial cells in culture and that recombinant IL-1 receptor antagonist (IL-1RA) significantly promotes epithelial cell growth in no feeder layer condition. In this study, we examined inhibitors of calpain, a cysteine proteinase that plays crucial roles in various cellular functions, including IL-1α maturation and secretion. The culturing of epithelial cells in serum-free media supplemented with a membrane-permeable calpain inhibitor significantly promoted growth while suppressing IL-1α maturation and secretion. By contrast, non-membrane-permeable calpain inhibitor treatment did not have these effects. Interestingly, immunoblotting analysis revealed that immature, untruncated, IL-1α expression was also downregulated by cell-permeable calpain inhibitor treatment, and the difference in IL-1α gene expression increased from day 2 to day 6. Although IL-1RA has been reported to promote epithelial cell growth, we detected no synergistic promotion of epithelial cell growth using a calpain inhibitor and IL-1RA. These findings indicate that calpain inhibitors promote epithelial cell proliferation by inhibiting IL-1α maturation at an early phase of epithelial cell culture and by suppressing the positive feedback-mediated amplification of IL-1α signalling.

Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies

Therapeutic strategies based on the principles of tissue engineering by self-assembly put forward the notion that functional regeneration can be achieved by utilising the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, in dilute ex vivo microenvironments, prolonged culture time is required to develop an extracellular matrix-rich implantable device. Herein, we assessed the influence of macromolecular crowding, a biophysical phenomenon that regulates intra- and extra-cellular activities in multicellular organisms, in human corneal fibroblast culture. In the presence of macromolecules, abundant extracellular matrix deposition was evidenced as fast as 48 h in culture, even at low serum concentration. Temperature responsive copolymers allowed the detachment of dense and cohesive supramolecularly assembled living substitutes within 6 days in culture. Morphological, histological, gene and protein analysis assays demonstrated maintenance of tissue-specific function. Macromolecular crowding opens new avenues for a more rational design in engineering of clinically relevant tissue modules in vitro.

Current wound healing procedures and potential care

In this review, we describe current and future potential wound healing treatments for acute and chronic wounds. The current wound healing approaches are based on autografts, allografts, and cultured epithelial autografts, and wound dressings based on biocompatible and biodegradable polymers. The Food and Drug Administration approved wound healing dressings based on several polymers including collagen, silicon, chitosan, and hyaluronic acid. The new potential therapeutic intervention for wound healing includes sustained delivery of growth factors, and siRNA delivery, targeting microRNA, and stem cell therapy. In addition, environment sensors can also potentially utilize to monitor and manage microenvironment at wound site. Sensors use optical, odor, pH, and hydration sensors to detect such characteristics as uric acid level, pH, protease level, and infection - all in the hopes of early detection of complications.

Efficient fabrication of epidermal cell sheets using γ-secretase inhibitor

BACKGROUND

Epidermal cell sheets have been utilized for regeneration of skin when skin defects occur and prevention of esophageal stricture after endoscopic submucosal dissection. To reduce the cost of cultivation, a novel culture method to shorten a culture process needs to be developed.

OBJECTIVES

To shorten a culture process of epidermal cell sheets, we developed a novel culture method to accelerate the fabrication of epidermal cell sheets using γ-secretase inhibitor.

METHODS

Normal human epidermal keratinocytes (NHEKs) were cultured using γ-secretase inhibitor, DAPT, during expansion of the cells to confluence and culture without DAPT during stratification. The cell growth, quantitative gene expression of stem/progenitor or differentiation markers, and protein expression of these markers were analyzed to verify the effectiveness of the novel method.

RESULTS

The proliferation of NHEKs on cell-culture inserts was promoted using DAPT. However, NHEKs were not stratified completely in the presence of DAPT. In contrast, NHEKs cultured using DAPT were stratified and differentiated by eliminating the inhibitor after the cells reached confluence. Real-time PCR analyses showed that the gene expressions of putative epithelial stem/progenitor cell markers and epidermis differentiation markers in the cell sheets fabricated using this novel method were significantly higher than those in the cell sheets fabricated without DAPT. Histological and immunofluorescence analyses revealed that it was possible to fabricate well-differentiated epidermal cell sheets efficiently by the novel culture method. The culture period was shortened to 67% of the time required for the control group. In feeder-free conditions, stratified epidermal cell sheets were also fabricated using DAPT.

CONCLUSIONS

The novel culture method using γ-secretase inhibitor, DAPT, was found to be effective for fabricating epidermal cell sheets.

Skin grafting for venous leg ulcers

BACKGROUND

Venous leg ulceration is a recurrent, chronic, disabling condition. It affects up to one in 100 people at some time in their lives. Standard treatments are simple dressings and compression bandages or stockings. Sometimes, despite treatment, ulcers remain open for months or years. Sometimes skin grafts are used to stimulate healing. These may be taken, or grown into a dressing, from the patient's own uninjured skin (autografts), or applied as a sheet of bioengineered skin grown from donor cells (allograft). Preserved skin from other animals, such as pigs, has also been used (xenografts).

OBJECTIVES

To assess the effect of skin grafts for treating venous leg ulcers.

SEARCH METHODS

For this update we modified the search strategies and conducted searches of The Cochrane Wounds Group Specialised Register (searched 27 July 2012); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 7); Ovid MEDLINE (2008 to July Week 3 2012); Ovid MEDLINE (In-Process & Other Non-Indexed Citations, July 26, 2012); Ovid EMBASE (2008 to 2012 Week 29); and EBSCO CINAHL (2008 to 26 July 2012). We did not apply date or language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of skin grafts in the treatment of venous leg ulcers.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook data extraction and assessment of study quality.

MAIN RESULTS

For this update of the review, we identified one new trial, bringing the total to 17 trials (1034 participants) - all of which were generally at moderate or high risk of bias. In 12 trials participants also received compression bandaging.Eleven trials compared a graft with standard care in which no graft was used. Two of these trials (102 participants) compared a dressing with an autograft; three trials (80 participants) compared frozen allografts with dressings, and two trials (45 participants) compared fresh allografts with dressings. Two trials (345 participants) compared tissue-engineered skin (bilayer artificial skin) with a dressing. In two trials (97 participants) a single-layer dermal replacement was compared with standard care.Six trials compared alternative skin grafting techniques. The first trial (92 participants) compared autografts with frozen allograft, a second (51 participants) compared a pinch graft (autograft) with porcine dermis (xenograft), the third (110 participants) compared growth-arrested human keratinocytes and fibroblasts with placebo, the fourth (10 participants) compared an autograft delivered on porcine pads with an autograft delivered on porcine gelatin microbeads, the fifth trial (92 participants) compared a meshed graft with a cultured keratinocyte autograft, and the sixth trial (50 participants) compared a frozen keratinocyte allograft with a lyophilised (freeze-dried) keratinocyte allografts.Significantly more ulcers healed when treated with bilayer artificial skin than with dressings. There was insufficient evidence from the other trials to determine whether other types of skin grafting increased the healing of venous ulcers.

AUTHORS' CONCLUSIONS

Bilayer artificial skin, used in conjunction with compression bandaging, increases venous ulcer healing compared with a simple dressing plus compression. Further research is needed to assess whether other forms of skin grafts increase ulcer healing.

Cell sheet technology for regeneration of esophageal mucosa

The progress of tissue-engineering technology has realized development of new therapies to treat various disorders by using cultured cells. Cell- and tissue-based therapies have been successfully applied to human patients, and several tissue-engineered products have been approved by the regulatory agencies and are commercially available. In the review article, we describe our experience of development and clinical application of cell sheet-based regenerative medicine. Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been shown to be useful for removal of gastrointestinal neoplasms with less invasiveness compared with open surgery, especially in esophageal surgery. However, postoperative inflammation and stenosis are major complications observed after intensive mucosal resection. Therefore, we have developed novel regenerative medicine to prevent such complications and promote wound healing of esophageal mucosa after EMR or ESD. Transplantable oral mucosal epithelial cell sheets were fabricated from patients’ own oral mucosa. Immediately after EMR or ESD, fabricated autologous cell sheets were endoscopically transplanted to the ulcer sites. We performed a preclinical study with a canine model. In human clinical settings, cell culture and cell sheet fabrication were performed in clean rooms according to good manufacturing practice guidelines, and pharmaceutical drugs were used as supplements to culture medium in place of research regents used in animal study. We believe that cell-based regenerative medicine would be useful to improve quality of life of patients after EMR or ESD.

Fabrication and validation of autologous human oral mucosal epithelial cell sheets to prevent stenosis after esophageal endoscopic submucosal dissection

OBJECTIVES

Human oral mucosal epithelial cells derived from 7 healthy volunteer donors were cultured in a clean room in a cell-processing center (CPC) according to good manufacturing practice guidelines. Cell culture and fabricated transplantable epithelial cell sheets were validated for treating ulcers after endoscopic mucosal dissection.

METHODS

The clonal growth and morphology of the human oral mucosal epithelial cells seeded on temperature-responsive surfaces were observed. During the cultivation, sterilization tests were performed to validate the environment in the CPC. To validate the purity and morphology of fabricated epithelial cell sheets, cell sheets harvested from temperature-responsive surfaces by temperature reduction were examined by histology and flow cytometry.

RESULTS

Human oral mucosal epithelial cells were successfully cultured and harvested as continuous cell sheets from temperature-responsive culture inserts without any animal-derived materials. During the cultivations, the sterile environment in the CPC was confirmed. The results of histological and flow cytometry analysis showed the high reproducibility of stratification and the purity of the fabricated human oral mucosal epithelial cell sheets.

CONCLUSIONS

The method for fabricating epithelial cell sheets shown in this study was suitable for the validation for clinical trials and suggested usability of the fabricated cell sheets.

Establishment of a murine epidermal cell line suitable for in vitro and in vivo skin modelling

Background

Skin diseases are a major health problem. Some of the most severe conditions involve genetic disorders, including cancer. Several of these human diseases have been modelled in genetically modified mice, thus becoming a highly valuable preclinical tool for the treatment of these pathologies. However, development of three-dimensional models of skin using keratinocytes from normal and/or genetically modified mice has been hindered by the difficulty to subculture murine epidermal keratinocytes.

Methods

We have generated a murine epidermal cell line by serially passaging keratinocytes isolated from the back skin of adult mice. We have termed this cell line COCA. Cell culture is done in fully defined media and does not require feeder cells or any other coating methods.

Results

COCA retained its capacity to differentiate and stratify in response to increased calcium concentration in the cell culture medium for more than 75 passages. These cells, including late passage, can form epidermis-like structures in three-dimensional in vitro models with a well-preserved pattern of proliferation and differentiation. Furthermore, these cells form epidermis in grafting assays in vivo, and do not develop tumorigenic ability.

Conclusions

We propose that COCA constitutes a good experimental system for in vitro and in vivo skin modelling. Also, cell lines from genetically modified mice of interest in skin biology could be established using the method we have developed. COCA keratinocytes would be a suitable control, within a similar background, when studying the biological implications of these alterations.

Fabrication of human oral mucosal epithelial cell sheets for treatment of esophageal ulceration by endoscopic submucosal dissection

BACKGROUND

Esophageal stenosis is one of the major complications of aggressive endoscopic resection. Tissue-engineered epithelial cell grafts have demonstrated effectiveness in promoting re-epithelialization and suppressing inflammation causing esophageal scarring and stenosis after endoscopic submucosal dissection (ESD) in an animal model.

OBJECTIVE

To confirm the reproducibility and efficacy of a human oral mucosal epithelial cell (hOMEC) sheet cultured on temperature-responsive surface in conformity with Good Manufacturing Practice guidelines.

DESIGN

A preclinical study.

SETTING

Good Manufacturing Practice grade cell-processing center, animal laboratory.

SUBJECTS

Canine esophageal ulcer models, which were made by ESD.

INTERVENTIONS

Oral mucosal specimens were obtained from 7 healthy volunteers.

MAIN OUTCOME MEASUREMENT

Fabricated and transplanted hOMEC sheets were subjected to histological analysis.

RESULTS

The reproducibility of the fabrication of hOMEC sheets was confirmed. In this method, animal-derived materials such as 3T3 feeder layer and fetal bovine serum were successfully excluded from the culture condition. Furthermore, the environment of the culture room and safety cabinet in the cell-processing center was maintained for obtaining sterility assurances during the fabrication. Transplanted hOMEC sheets after ESD were observed to graft onto canine esophageal ulcer surfaces.

LIMITATIONS

Small number of subjects, animal model.

CONCLUSIONS

Cultured hOMEC sheets were fabricated without animal-derived materials and demonstrated efficacy as a medical device that promotes re-epithelialization of an esophageal ulcer after ESD.

Preparation of keratinocyte culture medium for the clinical applications of regenerative medicine

Keratinocyte culture medium (KCM) has been used for the in vitro culture of keratinocytes and other types of epithelial cells, and the medium includes various ingredients. In this study, two modified KCMs were prepared. In the first, insulin, hydrocortisone and antibiotics that are normally included in KCM were replaced with clinically approved pharmaceutical agents, except transferrin and selenium; in the second, cholera toxin (CT) was replaced by L-isoproterenol (ISO). The modified KCMs were then compared to conventional KCM containing laboratory-grade reagents. Induced cell colony formations of canine oral mucosal epithelial cells cultured in both modified KCMs were found to be nearly equivalent to that in the control KCM, and there was no significant difference between the effect of CT and ISO. Canine oral mucosal cells proliferated to confluence in all three KCM formulations, with or without the use of 3T3 feeder layers. Cultured epithelial cells were harvested from temperature-responsive culture surfaces as an intact cell sheet, and the immunohistochemical analysis of the sheets showed that p63 and cytokeratin were expressed in the epithelial cell sheets cultured in all KCMs. Eventually, in the modified KCM formula, fetal bovine serum was replaced by autologous human serum, and the formula was found to be able to fabricate human oral mucosal epithelial cell sheets. These results indicated that the modified KCM was equally efficient as conventional KCM in the fabrication of transplantable stratified epithelial cell sheets.

Transplantation of chronic wounds with epidermal sheets derived from autologous hair follicles--the Leipzig experience

BACKGROUND

An increasing number of chronic wounds in our society require strategies to improve wound healing and wound closure. One of several options is skin transplantation. In this article, we focus on the transplantation of tissue engineered autologous epidermal sheets derived from outer root sheath (ORS) cells of the patients' hair.

PATIENTS AND METHODS

Out of the stem cells of the ORS of anagen hair, autologous keratinocytes are cultured ex vivo in organotypic cultures to form a multilayered epidermal equivalent (EpiDex, EuroDerm Biotech & Aesthetics, Stuttgart, Germany). These sheets are placed on the wound bed. Patients were observed twice a week in the first 2 weeks, then once weekly for 4 weeks, then every 4 weeks for up to 12 weeks after transplantation. A total of 23 patients with (n = 18) and without (n = 5) therapeutic improvement were analyzed retrospectively. We evaluated only the effect of a single transplantation in a selected ulcer per patient. Furthermore, a subgroup-analysis for responder patients with an ulcer area < 25 cm2 (n = 12) was performed.

RESULTS

In the responder patients (n = 18), a total wound reduction of 23% was observed. Patients (n = 12) with ulcer area < 25 cm2 had an improvement of 64%. Complete wound closure in this subgroup after a single transplantation was achieved in 33 % (n = 4) cases.

CONCLUSIONS

Autologous keratinocyte transplantation with EpiDex can be performed easily and safely in patients with chronic wounds with satisfying results. Our data suggest that patients with small ulcer area < 25 cm2 might profit the most from this method.

Mathematical model for wound healing following autologous keratinocyte transplantation

In times of increasing economical pressure on the health care systems, it is important to optimise the outpatient treatment of chronic wounds. Another aim of wound healing research is to discover agents to accelerate healing. Wound healing trajectories or healing velocities can provide information to demonstrate the endpoints for wound healing. A great problem in clinical trials is to specify these parameters. Therefore, we developed a mathematical model for more transparency. In this initial project, we observed 19 wounds to construct the wound healing trajectories after transplantation of autologous keratinocytes, and the results are so encouraging that investigation in this area will continue. The developed mathematical model describes the clinical observed healing process. It was possible to find parameters to distinguish between old and young patients, retrospectively or prospectively calculate the healing rates and to determine exactly the endpoint of healing. Therefore, our model might be very useful in practices or for studies.

Aplicação de substituto de pele em oncologia cutânea: estudo experimental com derme acelular e ceratinócitos cultivados

FUNDAMENTOS: As neoplasias malignas da pele de grandes dimensões apresentam dificuldades de reconstrução após a excisão. OBJETIVO: O objetivo deste estudo foi avaliar a exeqüibilidade de uma nova proposta de cobertura para feridas cirúrgicas criadas após a ressecção de grandes tumores cutâneos, a combinação da derme acelular humana com epitélio autólogo cultivado. MÉTODOS: A aplicação dos substitutos de pele foi feita em quatro pacientes com área de implante variando de 33 a 120 cm2. Além da observação dos resultados clínicos, realizou-se estudo morfológico para avaliação da integração dos implantes. RESULTADOS: Ceratinócitos autólogos cultivados foram enxertados em dois pacientes e não demonstraram integração. A derme acelular foi aplicada em quatro pacientes, sendo que em um deles foram feitas duas aplicações. Dos cinco implantes de derme acelular realizados, dois não apresentaram integração, em dois a integração foi de 70%, e de 50% no último. CONCLUSÃO: A cobertura imediata e definitiva de defeitos cirúrgicos através da aplicação de derme acelular humana combinada com epitélio autólogo cultivado é exeqüível. Em oncologia cutânea apenas em situações especiais o uso de substitutos de pele pode ser conveniente no sentido de evitar reconstruções mais complexas.

Reconstruction of functional tissues with cell sheet engineering

The field of tissue engineering has yielded several successes in early clinical trials of regenerative medicine using living cells seeded into biodegradable scaffolds. In contrast to methods that combine biomaterials with living cells, we have developed an approach that uses culture surfaces grafted with the temperature-responsive polymer poly(N-isoproplyacrylamide) that allows for controlled attachment and detachment of living cells via simple temperature changes. Using cultured cell sheets harvested from temperature-responsive surfaces, we have established cell sheet engineering to create functional tissue sheets to treat a wide range of diseases from corneal dysfunction to esophageal cancer, tracheal resection, and cardiac failure. Additionally, by exploiting the unique ability of cell sheets to generate three-dimensional tissues composed of only cultured cells and their deposited extracellular matrix, we have also developed methods to create thick vascularized tissues as well as, organ-like systems for the heart and liver. Cell sheet engineering therefore provides a novel alternative for regenerative medicine approaches that require the re-creation of functional tissue structures.

Regeneration of squamous epithelia from stem cells of cultured grafts

The only cultured cell types extensively used for tissue regeneration are the keratinocyte and the chondrocyte. Cultured autologous keratinocytes derived from the epidermis have been used for many years to produce grafts that regenerate an epidermis over a full-thickness wound, such as a third-degree burn. But there have been many failures of engraftment, and in the absence of criteria for the quality of the cultures, the causes of failure cannot be analyzed. It has become clear that the essential feature of the graft is the presence of an adequate number of stem cells. This article describes the criteria for estimating that number. Advances in graft preparation, combining better preservation of stem cells with ease of application of the graft, are also described. These improvements have been applied to cultures of ocular limbal cells, which contain the keratinocyte stem cells of the corneal epithelium. Cultures meeting the criteria of stem cell number have been grafted to 116 patients suffering from chemical destruction of the limbus. The procedure has been highly successful in the alleviation of suffering and the restoration of vision.

Skin grafting for venous leg ulcers

BACKGROUND

Venous leg ulceration is a recurrent, chronic, disabling condition. It affects up to one in 100 adults at some time. Standard treatments are simple dressings and compression bandages or stockings. Sometimes, despite treatment, ulcers remain open for months or years. Sometimes skin grafts are used to stimulate healing. These may be taken, or grown into a dressing, from the patient's own uninjured skin (autografts), or applied as a sheet of bioengineered skin grown from donor cells (allograft). Preserved skin from other animals, such as pigs, has also been used (xenografts).

OBJECTIVES

To assess the effect of skin grafts for treating venous leg ulcers.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Register (February 2006) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2006).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of skin grafts in the treatment of venous leg ulcers.

DATA COLLECTION AND ANALYSIS

Two reviewers independently undertook data extraction and assessment of study quality.

MAIN RESULTS

We identified 15 trials - generally of poor methodological quality - involving 768 participants. In 11 trials participants also received compression bandaging. One trial (31 participants) compared a dressing with an autograft. Three trials (74 participants) compared frozen allografts with dressings, and three trials (47 participants) compared fresh allografts with dressings. Two trials (345 participants) compared tissue-engineered skin (bilayer artificial skin) with a dressing. In two trials (71 participants) a single-layer dermal replacement was compared with standard care. Four trials compared skin grafting techniques: one trial (92 participants) compared autografts with frozen allograft, a second (51 participants) compared a pinch graft (autograft) with a porcine dermis (xenograft), the third (seven participants, 12 ulcers) compared tissue-engineered skin with a split-thickness graft, the fourth (10 participants) compared a fresh allograft with a frozen allograft. The trials comparing bilayer artificial skin with a dressing reported a significantly higher proportion of ulcers healing with artificial skin. There was not enough evidence from the other trials to determine whether other types of skin grafting increased the healing of venous ulcers.

AUTHORS' CONCLUSIONS

Bilayer artificial skin, used in conjunction with compression bandaging, increases the chance of healing a venous ulcer compared with compression and a simple dressing. Further research is needed to assess whether other forms of skin grafts increase ulcer healing.

Corneal epithelial stem cell delivery using cell sheet engineering: not lost in transplantation

Cell-based therapies have now generated significant interest as novel drug delivery systems, with various adult cell types used in treating a wide range of diseases. To overcome the limits that restrict treatments for corneal surface dysfunction, corneal epithelial stem cells expanded ex vivo have been applied as an alternative approach. While previous studies used various carrier substrates, we present a novel method using cell sheet engineering with temperature-responsive culture dishes to create carrier-free corneal epithelial stem cell sheets that can be transplanted without sutures. Results from clinical trials reveal successful transplantation with the recovery of lost visual acuity in all cases. Cell sheet engineering, therefore, presents a novel method for the delivery of corneal epithelial stem cells, and can also be applied for other approaches of cellular therapeutics.

The effect of micropores in the surface of temperature-responsive culture inserts on the fabrication of transplantable canine oral mucosal epithelial cell sheets

Primary canine oral mucosal epithelial cells were cultured on temperature-responsive dishes and cell culture inserts to fabricate transplantable epithelial cell sheets. When 3T3 feeder layers and fetal bovine serum were eliminated from dish culture, the harvested cell sheets became significantly more fragile. In contrast, when epithelial cells were cultured on inserts having submicron-scale pores, cell sheet fragility was eliminated. Keratin expression profiles showed no differences among the harvested cell sheets, but the expression of p63, a putative stem/progenitor marker, was strongly dependent on the presence of 3T3 feeder layers and serum. These results suggest that the maintenance of stem/progenitor cells is influenced by the apical/basal supply of nutrients as well as culture supplements.

Enxertia de pele em oncologia cutânea

Em oncologia cutânea depara-se freqüentemente com situações em que a confecção de um enxerto é uma boa alternativa para o fechamento do defeito cirúrgico. Conhecer aspectos referentes à integração e contração dos enxertos é fundamental para que os cirurgiões dermatológicos procedam de maneira a não contrariar princípios básicos do transplante de pele. Os autores fazem uma revisão da classificação e fisiologia dos enxertos de pele, acrescendo considerações cirúrgicas determinantes para o sucesso do procedimento.

Fabrication of transplantable human oral mucosal epithelial cell sheets using temperature-responsive culture inserts without feeder layer cells

To exclude bacteria- or animal-derived factors from cultured fabrication of transplantable epithelial cell sheets, primary human oral mucosal epithelial cells were seeded on temperature-responsive culture inserts having submicron-scale pores. Supplying culture medium containing human autologous serum to both apical and basal sides of human epithelial cells allows these cells to grow to confluence. These proliferating cells created stratified epithelial layers even when 3T3 feeder layers and fetal bovine serum were eliminated from culture. Normal keratin expression profiles were obtained with these cells, and basal and midlayer cells expressed p63, a putative stem/progenitor marker. These results suggest that temperature-responsive culture inserts can be useful in clinical settings that require the exclusion of xenogeneic factors.

Evaluation of ApligrafR persistence and basement membrane restoration in donor site wounds: a pilot study

Apligraf is a bilayered tissue-engineered product consisting of a bovine collagen matrix with neonatal fibroblasts, overlaid by a stratified epithelium containing living keratinocytes. The United States Food and Drug Administration has approved its use for venous leg ulcers and neuropathic diabetic foot ulcers. Apligraf provides a dermal matrix and produces cytokines similar to the human skin. However, its mechanism of action and ultimate fate in host wounds are unclear. The aim of this study was to evaluate the persistence of Apligraf fibroblasts and keratinocytes in human acute partial-thickness wounds (split-thickness donor sites) treated with Apligraf. In an open-label, within-patient, three-centered, controlled pilot study, 10 patients were treated with Apligraf, Apligraf dermis only (without epidermis), and a polyurethane film for donor site wounds of the same size, depth, and anatomical location. Apligraf DNA persistence was the primary outcome measure. Basement membrane components, cosmetic outcome, time to wound healing, and safety parameters were secondary outcome measures. One week after the initial treatment, reverse transcription polymerase chain reaction analysis found that two Apligraf and two Apligraf dermis-only-treated sites had Apligraf DNA present. Four weeks posttreatment, only one Apligraf and one Apligraf dermis-only sites showed the presence of Apligraf DNA. There was no difference between the three treatment modalities in establishing basement membrane in donor site wounds. No differences in other secondary outcomes were found. Apligraf DNA persisted in a minority of patients at 4 weeks in acute partial-thickness wounds. Apligraf's success in speeding healing of acute wounds appears to be related to factors other than the persistence of donor DNA or effect on basement membrane restoration.

Cell delivery in regenerative medicine: the cell sheet engineering approach

Recently, cell-based therapies have developed as a foundation for regenerative medicine. General approaches for cell delivery have thus far involved the use of direct injection of single cell suspensions into the target tissues. Additionally, tissue engineering with the general paradigm of seeding cells into biodegradable scaffolds has also evolved as a method for the reconstruction of various tissues and organs. With success in clinical trials, regenerative therapies using these approaches have therefore garnered significant interest and attention. As a novel alternative, we have developed cell sheet engineering using temperature-responsive culture dishes, which allows for the non-invasive harvest of cultured cells as intact sheets along with their deposited extracellular matrix. Using this approach, cell sheets can be directly transplanted to host tissues without the use of scaffolding or carrier materials, or used to create in vitro tissue constructs via the layering of individual cell sheets. In addition to simple transplantation, cell sheet engineered constructs have also been applied for alternative therapies such as endoscopic transplantation, combinatorial tissue reconstruction, and polysurgery to overcome limitations of regenerative therapies and cell delivery using conventional approaches.

Altered phenotype of cultured urothelial and other stratified epithelial cells: implications for wound healing

The differentiation of cultured stratified epithelial cells can deviate significantly from that of normal epithelium, leading to suggestions that cultured cells undergo abnormal differentiation, or a truncated differentiation. Thus cultured epidermal and corneal epithelial cells stop synthesizing their tissue-specific keratin pair K1/K10 and K3/K12, respectively. The replacement of these keratins in the suprabasal compartment by K6/K16 keratins that are made by all stratified squamous epithelia during hyperplasia rules out a truncated differentiation. Importantly, the keratin pattern of in vivo corneal epithelium undergoing wound repair mimics that of cultured rabbit corneal epithelial cells. Although cultured urothelial cells continue to synthesize uroplakins, which normally form two-dimensional crystalline urothelial plaques covering almost the entire apical urothelial surface, these proteins do not assemble into crystals in cultured cells. Cultured epithelial cells can, however, rapidly regain normal differentiation on the removal of mitogenic stimuli, the use of a suitable extracellular matrix, or the transplantation of the cells to an in vivo, nonmitogenic environment. These data suggest that cultured epithelial cells adopt altered differentiation patterns mimicking in vivo regenerating or hyperplastic epithelia. Blocking the synthesis of tissue-specific differentiation products, such as the K1 and K10 keratins designed to form extensive disulfide cross-links in cornified cells, or the assembly of uroplakin plaques allows epithelial cells to better migrate and proliferate, activities that are of overriding importance during wound repair. Cultured urothelial and other stratified epithelial cells provide excellent models for studying the regulation of the synthesis and assembly of differentiation products, a key cellular process during epithelial wound repair.