Nathalie Hirt-Burri

Tissue engineered fetal skin constructs for paediatric burns

Autologous skin-grafting is the gold standard for treatment of deep second and third degree burns. Available bioengineered skin products also necessitate this two-step surgical procedure. Therefore, we developed fetal skin constructs to improve healing of such degree burns. A bank of fetal skin cells was developed from one organ donation (4 cm2 of skin allowing the preparation of several million three-dimensional skin constructs, 9x12 cm, on native horse collagen). Successive fetal constructs were applied to eight patients at every change of dressing during 1-3 weeks in an outpatient setting. Complete closure was rapid (mean 15.3 days [SD 5.5]) with little hypertrophy of new skin and no retraction seen. This simple technique provided complete treatment without auto-grafting, showing that fetal skin cells might have great potential to treat burns and eventually acute and chronic wounds of other types.

Chronic wound healing by fetal cell therapy may be explained by differential gene profiling observed in fetal versus old skin cells

Engineering of fetal tissue has a high potential for the treatment of acute and chronic wounds of the skin in humans as these cells have high expansion capacity under simple culture conditions and one organ donation can produce Master Cell Banks which can fabricate over 900 million biological bandages (9 x 12cm). In a Phase 1 clinical safety study, cases are presented for the treatment of therapy resistant leg ulcers. All eight patients, representing 13 ulcers, tolerated multiple treatments with fetal biological bandages showing no negative secondary effects and repair processes similar to that seen in 3rd degree burns. Differential gene profiling using Affymetrix gene chips (analyzing 12,500 genes) were accomplished on these banked fetal dermal skin cells compared to banked dermal skin cells of an aged donor in order to point to potential indicators of wound healing. Families of genes involved in cell adhesion and extracellular matrix, cell cycle, cellular signaling, development and immune response show significant differences in regulation between banked fetal and those from banked old skin cells: with approximately 47.0% of genes over-expressed in fetal fibroblasts. It is perhaps these differences which contribute to efficient tissue repair seen in the clinic with fetal cell therapy.

Whole-Cell Bioprocessing of Human Fetal Cells for Tissue Engineering of Skin

Current restrictions for human cell-based therapies have been related to technological limitations with regards to cellular proliferation capacity (simple culture conditions), maintenance of differentiated phenotype for primary human cell culture and transmission of communicable diseases. Cultured primary fetal cells from one organ donation could possibly meet the exigent and stringent technical aspects for development of therapeutic products. Master and working cell banks from one fetal organ donation (skin) can be developed in short periods of time and safety tests can be performed at all stages of cell banking. For therapeutic use, fetal cells can be used up to two thirds of their life-span in an out-scaling process and consistency for several biological properties includes protein concentration, gene expression and biological activity. As it is the intention that banked primary fetal cells can profit from the prospected treatment of hundreds of thousands of patients with only one organ donation, it is imperative to show consistency, tracability and safety of the process including donor tissue selection, cell banking, cell testing and growth of cells in out-scaling for the preparation of whole-cell tissue-engineering products.

Consistency and safety of cell banks for research and clinical use: preliminary analysis of fetal skin banks.

Current restrictions for human cell-based therapies have been related to technological limitations with regards to cellular proliferation capacity, maintenance of differentiated phenotype for primary human cell culture, and transmission of communicable diseases. We have seen that cultured primary fetal cells from one organ donation could possibly meet the exigent and stringent technical aspects for development of therapeutic products. We could develop a master cell bank (MCB) of 50 homogenous ampoules of 4–5 million cells each from one fetal organ donation (skin) in short periods of time compared to other primary cell types. Safety tests were performed at all stages of the cell banking. MCB ampoules could create a working cell bank to be used for clinical or research use. Monolayer culture of fetal skin cells had a life span of 12–17 passages, and independent cultures obtained from the same organ donation were consistent for protein concentration (with 1.4-fold maximal difference between cultures) as well as gene expression of MMP-14, MMP-3, TIMP-3, and VEGF (1.4-, 1.9-, 2.1-, and 1.4-fold maximal difference between cultures, respectively). Cell cultures derived from four independent fetal skin donations were consistent for cell growth, protein concentration, and gene expression of MDK, PTN, TGF-β1, and OPG. As it is the intention that banked primary fetal cells can profit from the potential treatment of hundreds of thousands of patients with only one organ donation, it is imperative to show consistency, tracability, and safety of the process, including donor tissue selection, cell banking, cell testing, and growth of cells in upscaling for the preparation of cell transplantation.

Wound-healing Gene Family Expression Differences Between Fetal and Foreskin Cells Used for Bioengineered Skin Substitutes

For tissue engineering, several cell types and tissues have been proposed as starting material. Allogenic skin products available for therapeutic usage are mostly developed with cell culture and with foreskin tissue of young individuals. Fetal skin cells offer a valuable solution for effective and safe tissue engineering for wounds due to their rapid growth and simple cell culture. By selecting families of genes that have been reported to be implicated in wound repair and particularly for scarless fetal wound healing including transforming growth factor-beta (TGF-beta) superfamily, extracellular matrix, and nerve/angiogenesis growth factors, we have analyzed differences in their expression between fetal skin and foreskin cells, and the same passages. Of the five TGF-beta superfamily genes analyzed by real-time reverse transcription-polymerase chain reaction, three were found to be significantly different with sixfold up-regulated for TGF-beta2, and 3.8-fold for BMP-6 in fetal cells, whereas GDF-10 was 11.8-fold down-regulated. For nerve growth factors, midkine was 36-fold down-regulated in fetal cells, and pleiotrophin was 4.76-fold up-regulated. We propose that fetal cells present technical and therapeutic advantages compared to foreskin cells for effective cell-based therapy for wound management, and overall differences in gene expression could contribute to the degree of efficiency seen in clinical use with these cells.

Human fetal bone cells in delivery systems for bone engineering

The aim of this study was to culture human fetal bone cells (dedicated cell banks of fetal bone derived from 14 week gestation femurs) within both hyaluronic acid gel and collagen foam, to compare the biocompatibility of both matrices as potential delivery systems for bone engineering and particularly for oral application. Fetal bone cell banks were prepared from one organ donation and cells were cultured for up to 4 weeks within hyaluronic acid (Mesolis®) and collagen foams (TissueFleece®). Cell survival and differentiation were assessed by cell proliferation assays and histology of frozen sections stained with Giemsa, von Kossa and ALP at 1, 2 and 4 weeks of culture. Within both materials, fetal bone cells could proliferate in three‐dimensional structure at ∼70% capacity compared to monolayer culture. In addition, these cells were positive for ALP and von Kossa staining, indicating cellular differentiation and matrix production. Collagen foam provides a better structure for fetal bone cell delivery if cavity filling is necessary and hydrogels would permit an injectable technique for difficult to treat areas. In all, there was high biocompatibility, cellular differentiation and matrix deposition seen in both matrices by fetal bone cells, allowing for easy cell delivery for bone stimulation in vivo. Copyright

Biologicals and Fetal Cell Therapy for Wound and Scar Management

Few biopharmaceutical preparations developed from biologicals are available for tissue regeneration and scar management. When developing biological treatments with cellular therapy, selection of cell types and establishment of consistent cell banks are crucial steps in whole-cell bioprocessing. Various cell types have been used in treatment of wounds to reduce scar to date including autolog and allogenic skin cells, platelets, placenta, and amniotic extracts. Experience with fetal cells show that they may provide an interesting cell choice due to facility of outscaling and known properties for wound healing without scar. Differential gene profiling has helped to point to potential indicators of repair which include cell adhesion, extracellular matrix, cytokines, growth factors, and development. Safety has been evidenced in Phase I and II clinical fetal cell use for burn and wound treatments with different cell delivery systems. We present herein that fetal cells present technical and therapeutic advantages compared to other cell types for effective cell-based therapy for wound and scar management.

Insurance coverage of pediatric burns: Switzerland versus USA

Burn care and research have significantly improved over the past years. However, insurance coverage of such treatments does not reflect the improvements in this multi-disciplinary field. Government insurance policies in first world countries renown for burn care treatment, such as Switzerland and the United States, have not adapted to the complexity and longitudinal nature of burn care. Using case studies from both countries, we have analyzed both the institutional and policy approach to pediatric burn treatment coverage. Subsequently, by presenting the Shriners burn care model, we offer a policy recommendation to both the Swiss and the American governments to better their present legislation and infrastructure on pediatric burn coverage.

Cell Therapy Assistance in Reconstructive Surgery for Musculoskeletal Tissues Following Burn and Trauma: Swiss Cellular TransplantationPlatform

Health issues for severe burns and trauma affecting populations from both civilian and military can have many similarities. Much of the medical progress for treatment and surgical care has been documented during times of catastrophic events and war. Death and morbidity of military personnel due to blast and combat-related injuries has declined as a result of improved surgical management, faster transport, and the use of antibiotics. Integration of cellular therapies could aid in repairing damaged tissues more rapidly. As bio-engineered cells and materials would be readily available, they could rapidly be used in the military settings, especially for the treatment of burns and trauma. Cell sources that can be easily expanded and stocked (allogenic sources) would be interesting cell sources to have developed to avoid the biopsy from the patient and the time necessary to prepare the cells before treatment. Cell sources can originate from both animal and human and at all periods of development extending from embryonic to adult. Cell sources can be technically demanding or they can be developed from primary tissue and the resulting cells can remain more similar to their original state. The use of progenitor cells have been developed in a unique Federal Transplantation Program Registration in Switzerland (cell lines have been described and deposited in the European Protection Agency Cell Depository, Porton Down’s) should help to advance cellular therapy programs with qualified material that is available when needed for both soft and hard tissues that have been injured. We will give an overview of: i) cell therapies used in military practice to date; ii) Description of cell types and cell choices for regenerative medicine; and iii) The organization of the progenitor cell therapy platform in Switzerland; iv) Pre-requisite recommendations for the future of using cell therapies in world defense and human security.

Progenitor Skin Cell Therapy and Evolution of Medical Applications

Organs and cells can be efficiently used and transformed into intermediate or final products that propose many advances in new medical technology from skin grafting to 3D micro-tissues for biocompatibility and industry testing. For instance, cell sources that can be easily expanded and stocked from allogeneic sources would be interesting in order to avoid the biopsy from the patient and the time necessary to prepare the cells before treatments of patients. Also, cell sources used historically in medicine can provide enough banked cells not only designated for treatment of patients but also for developing innovative testing platforms with uniform primary cell populations.