Bioartificial Esophagus in the Era of Tissue Engineering

4 April 2013

Surgical repair and bridging of the esophagus in newborns with esophageal atresia by primary anastomosis is successful in the majority of cases, whereas bridging of long-gap esophageal atresia is still a surgical challenge. In theses situations, delayed repair (primary hitching of the esophagus end to the prevertebral fascia or the Foker technique), myotomy, and esophageal replacement with either gastric, jejunum, or colon transposition are possible therapeutic options. However, these techniques result in substantial morbidity and mortality rates. Moreover disabling symptoms related to late complications such as anastomotic strictures, reflux, and delayed conduit emptying impair the patient’s quality of life. In our preliminary study in a pig model, we established, that short circumferential replacement of the cervical esophagus by a fresh aortic allograft allowed long-term patency of the esophageal lumen and nutritional autonomy. The main limit of this approach was the absence of tissue remodeling leading to the lack of contractility and propulsive capacity of the graft area.

Tissue engineering (TE) is an interdisciplinary field which applies the principles of engineering and life sciences to the development of biological substitutes that restore, maintain or improve tissue function. The underlying principle of tissue engineering involves using isolated autologous cells combined with complex biomaterials and cultivating new tissues and organs in vitro and/or in vivo.

In 2009, we initiated a program of oesophageal TE using a hybrid approach in a pig model. As a first step, we demonstrated the feasibility of culturing porcine and human myoblasts and porcine oral epithelial cells on acellular scaffolds. The optimal cell culture duration on scaffolds before in vivo implantation was 7 days, whatever the cell type. Myoblast of both sources should be seeded at 0.5×106 cells /cm². For porcine oral epithelial cells an initial concentration of 106 cells /cm² was preferable to obtain a consequent amount of cells at D7. The total duration for in vitro substitute preparation was 21 days (14 days for cell expansion and 7 days for scaffold culture).

Then, a circumferential replacement of the cervical esophagus using this substitute was performed in 18 pigs under the cover of an esophageal stent, followed by sequential sacrifices (3 – 6 – 9 – 12 months) in order to analyze the tissue remodeling process. Pigs acquired a nutritional autonomy in the long term, which remained after stent removal by month 3 post-replacement. By month 7, analysis of the specimens showed the appearance of an esophageal phenotype, with a well differentiated epithelium, sub-mucosal glands and muscle fibers organized in fascicules. Results after longer follow up are awaited.

In parallel, we are currently investigating the tissue assembly of an acellular matrix seeded in vitro by mesenchymal stem cells, according the same protocol. These cells are endowed with in vitro multilineage differentiation abilities and constitute an attractive autologous source of material for cell therapy.

This project, which is in part funded by the Association Française de l’Atrésie de l’Oesophage (AFAO) since its beginning, is being coordinated and supervised by the clinical research unit of the Saint Louis Hospital in Paris, France — the Clinical Investigation Centre in Biotherapies (CIC – BT) — specialized in the evaluation of biotherapies and responsible for the synchronization of hospital projects as well as the implementation of clinical trials, in collaboration with the National Reference Center for Congenital Oesophageal Anomalies in Lille It is within the cellular therapy unit of the Saint Louis Hospital, where the esophageal substitute are prepared and in the IMPRT-IFR 114,Hospital Department for Experimental Research, University of Lille-North of France, where the esophageal replacement are performed in pigs.

 

Tigran Poghosyan, MD 1, 2, Rony Sfeir MD 3, Jerome Larghero, Pharm D, PhD 2, Sebastien Gaujoux, MD1, Laurent Michaud3 Pierre Cattan, MD, PhD 1, 2.
1 Department of Digestive and Endocrine Surgery, Saint-Louis Hospital, Paris, France
2 Cellular Therapy Unit – Clinical Investigation Centre in Biotherapies CIC-BT501– INSERM UMR 940, Saint-Louis Hospital, Paris, France
3 National Reference Center for Congenital Oesophageal Anomalies Jeanne de Flandre Hospital, Lille, France

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