Short Bowel Syndrome (SBS) in children is a condition of intestinal malabsorption and dysmotility, caused by rare congenital malformations or acquired diseases, requiring extensive bowel surgical resection which in severe cases can lead to irreversible intestinal failure.
Nowadays, the management of pediatric patients affected by SBS is multidisciplinary, involving different possible strategies of treatment: total parenteral nutrition, surgical intestinal lengthening up to intestinal transplantation. The main aim of all these approaches is to promote bowel absorption, but none of them is free from complications that may impair children quality of life.
Based on these considerations, this Research Project aims to identify new options to manage and treat SBS. Hence, two aspects were considered: a clinical and an experimental one.
As known, the management of SBS patients requires a careful follow-up by a multispecialistic team, able to survey their possible short- and long-term complications and their progressive weaning from parenteral support. Considered this, the clinical part of this Research Project focused on the evaluation of citrulline as a reliable serum marker of residual bowel function. The goal was to verify the possibility of suggesting it for routine dosage in case of intestinal failure, similarly to creatinine in renal impairment and for transaminases in hepatic failure.
Briefly, we identified a sample population consisting of 10 SBS patients, age ≤ 5 years and residual bowel length (after surgery) ≤ 100 cm. Patients followed-up with parenteral and enteral nutrition programs and were subjected to citrulline dosages at least 6 weeks after surgery.
At the end of the clinical evaluation, we highlighted that serum values of citrulline are strongly related with both the residual intestinal length and the duration of their dependence on parenteral support (p < 0.01).
Likewise, the experimental research turned its attention to Tissue Engineering that is a new medical science which aims to achieve functionally active tissue substitutes by scaffolds, cells and growth factors.
The second part of the Research Project focused on the possibility to develop a bio-synthetic scaffold for tissue engineering applications in SBS. We manufactured, according to a protocol we patented, new hydrogels based on polyvinyl alcohol with a degree of oxidation of 1% and 2% respectively. The purpose of the chemical oxidation was to confer to the derived biomaterial a certain biodegradation rate. Hence, oxidized hydrogels obtained via physical cross-linking (freezing-thawing) were compared to native PVA hydrogels for their morpho-mechanical and biological properties by means of ultrastructural analysis with scanning electron microscopy, tensile tests, swelling index analysis, and in vivo biodegradation studies. These investigations showed that the strength and the stiffness of the polymer are significantly related to the chemical modification as they decrease along with the oxidation degree; conversely, the swelling and the biodegradation rate increase along with it.
The obtained results led us to identify in scaffolds prepared by using 1% Oxidized PVA the supports with the most adequate morpho-mechanical and biodegradation properties to our purposes. Hereafter, it was set up a composite scaffold in 1% Oxidized PVA cross-linked with decellularized intestinal extracellular matrix (ECM). The combination of the polymer with the bioactive matrix allowed us to obtain a support with good mechanical properties and able to promote cell growth and proliferation.
Briefly, the small intestine of adult rats was removed and decellularized according to the detergent-enzymatic protocol by Meezan. After having assessed the effectiveness of the procedure (DAPI staining) the acellular matrix was characterized by histological staining (hemotoxylin/eosin). Thereafter, the extracellular matrix (intact and homogenized) was crosslinked with 1% Oxidized PVA and the ability of the composite scaffold to support cell adhesion and proliferation was investigated using a primary culture of adipose mesenchymal stem cells. After 7 days from seeding, a significant cell growth on the composite scaffolds was observed in comparison with the nude polymeric support. Finally, based on of the TESI (Small Intestine Tissue Engineering) model, the scaffold was implanted in the omentum of adult rats; after 4-weeks, composite scaffolds demonstrated their ability to induce the formation of a composite pseudoepithelial tissue with intestinal-like features
