Giorgia Totonelli

A rat decellularized small bowel scaffold that preserves villus-crypt architecture for intestinal regeneration

Management of intestinal failure remains a clinical challenge and total parenteral nutrition, intestinal elongation and/or transplantation are partial solutions. In this study, using a detergent-enzymatic treatment (DET), we optimize in rats a new protocol that creates a natural intestinal scaffold, as a base for developing functional intestinal tissue. After 1 cycle of DET, histological examination and SEM and TEM analyses showed removal of cellular elements with preservation of the native architecture and connective tissue components. Maintenance of biomechanical, adhesion and angiogenic properties were also demonstrated strengthen the idea that matrices obtained using DET may represent a valid support for intestinal regeneration.

Discarded human kidneys as a source of ECM scaffold for kidney regeneration technologies

In the United States, more than 2600 kidneys are discarded annually, from the total number of kidneys procured for transplant. We hypothesized that this organ pool may be used as a platform for renal bioengineering and regeneration research. We previously showed that decellularization of porcine kidneys yields renal extracellular matrix (ECM) scaffolds that maintain their basic components, support cell growth and welfare in vitro and in vivo, and show an intact vasculature that, when such scaffolds are implanted in vivo, is able to sustain physiological blood pressure. The purpose of the current study was to test if the same strategy can be applied to discarded human kidneys in order to obtain human renal ECM scaffolds. The results show that the sodium dodecylsulfate-based decellularization protocol completely cleared the cellular compartment in these kidneys, while the innate ECM framework retained its architecture and biochemical properties. Samples of human renal ECM scaffolds stimulated angiogenesis in a chick chorioallantoic membrane assay. Importantly, the innate vascular network in the human renal ECM scaffolds retained its compliance. Collectively, these results indicate that discarded human kidneys are a suitable source of renal scaffolds and their use for tissue engineering applications may be more clinically applicable than kidneys derived from animals.

Esophageal tissue engineering: A new approach for esophageal replacement

A number of congenital and acquired disorders require esophageal tissue replacement. Various surgical techniques, such as gastric and colonic interposition, are standards of treatment, but frequently complicated by stenosis and other problems. Regenerative medicine approaches facilitate the use of biological constructs to replace or regenerate normal tissue function. We review the literature of esophageal tissue engineering, discuss its implications, compare the methodologies that have been employed and suggest possible directions for the future. Medline, Embase, the Cochrane Library, National Research Register and ClinicalTrials.gov databases were searched with the following search terms: stem cell and esophagus, esophageal replacement, esophageal tissue engineering, esophageal substitution. Reference lists of papers identified were also examined and experts in this field contacted for further information. All full-text articles in English of all potentially relevant abstracts were reviewed. Tissue engineering has involved acellular scaffolds that were either transplanted with the aim of being repopulated by host cells or seeded prior to transplantation. When acellular scaffolds were used to replace patch and short tubular defects they allowed epithelial and partial muscular migration whereas when employed for long tubular defects the results were poor leading to an increased rate of stenosis and mortality. Stenting has been shown as an effective means to reduce stenotic changes and promote cell migration, whilst omental wrapping to induce vascularization of the construct has an uncertain benefit. Decellularized matrices have been recently suggested as the optimal choice for scaffolds, but smart polymers that will incorporate signalling to promote cell-scaffold interaction may provide a more reproducible and available solution. Results in animal models that have used seeded scaffolds strongly suggest that seeding of both muscle and epithelial cells on scaffolds prior to implantation is a prerequisite for complete esophageal replacement. Novel approaches need to be designed to allow for peristalsis and vascularization in the engineered esophagus. Although esophageal tissue engineering potentially offers a real alternative to conventional treatments for severe esophageal disease, important barriers remain that need to be addressed.

Preservation of micro-architecture and angiogenic potential in a pulmonary acellular matrix obtained using intermittent intra-tracheal flow of detergent enzymatic treatment

Tissue engineering of autologous lung tissue aims to become a therapeutic alternative to transplantation. Efforts published so far in creating scaffolds have used harsh decellularization techniques that damage the extracellular matrix (ECM), deplete its components and take up to 5 weeks to perform. The aim of this study was to create a lung natural acellular scaffold using a method that will reduce the time of production and better preserve scaffold architecture and ECM components. Decellularization of rat lungs via the intratracheal route removed most of the nuclear material when compared to the other entry points. An intermittent inflation approach that mimics lung respiration yielded an acellular scaffold in a shorter time with an improved preservation of pulmonary micro-architecture. Electron microscopy demonstrated the maintenance of an intact alveolar network, with no evidence of collapse or tearing. Pulsatile dye injection via the vasculature indicated an intact capillary network in the scaffold. Morphometry analysis demonstrated a significant increase in alveolar fractional volume, with alveolar size analysis confirming that alveolar dimensions were maintained. Biomechanical testing of the scaffolds indicated an increase in resistance and elastance when compared to fresh lungs. Staining and quantification for ECM components showed a presence of collagen, elastin, GAG and laminin. The intratracheal intermittent decellularization methodology could be translated to sheep lungs, demonstrating a preservation of ECM components, alveolar and vascular architecture. Decellularization treatment and methodology preserves lung architecture and ECM whilst reducing the production time to 3 h. Cell seeding and in vivo experiments are necessary to proceed towards clinical translation.

The predictive value of preoperative fluorine-18-L-3,4-dihydroxyphenylalanine positron emission tomography-computed tomography scans in children with congenital hyperinsulinism of infancy.

BACKGROUND/PURPOSE In congenital hyperinsulinism (CHI) of infancy, the use of preoperative fluorine-18-L-3,4-dihydroxyphenylalanine-positron emission tomography-computed tomography ((18)F-DOPA-PET-CT) scan has recently been reported. The aim of this study was to evaluate the accuracy of this technique in discriminating between diffuse and focal CHI and the anatomical localization of focal lesions. METHODS Between 2006 and 2010, (18)F-DOPA-PET scan was performed in 19 children with CHI (median age, 2 months; range, 1-12 months) who were not responding to medical therapy and underwent laparoscopic or open surgery. The findings of (18)F-DOPA-PET scan were correlated with histology. RESULTS In 5 children, (18)F-DOPA-PET scan showed diffuse pancreatic uptake, confirmed at histology and supporting the genetic suspicion of diffuse disease. In 14 children, (18)F-DOPA-PET scan indicated focal pancreatic uptake, which corresponded to histology. However, in 5 patients (36%), (18)F-DOPA-PET scan was inaccurate in defining the location of the lesion (n = 3), size of the lesion (n = 1), or both location and size (n = 1), leading to an inaccurate pancreatic resection. CONCLUSIONS Fluorine-18-L-3,4-dihydroxyphenylalanine-positron emission tomography-computed tomography scan discriminates between diffuse and focal forms of CHI. In focal forms, (18)F-DOPA-PET scan is useful in 2/3 of patients in defining the site and dimension of the focal lesion. Intraoperative histologic confirmation of complete focal lesion resection is needed.

A decellularization methodology for the production of a natural acellular intestinal matrix.

Successful tissue engineering involves the combination of scaffolds with appropriate cells in vitro or in vivo. Scaffolds may be synthetic, naturally-derived or derived from tissues/organs. The latter are obtained using a technique called decellularization. Decellularization may involve a combination of physical, chemical, and enzymatic methods. The goal of this technique is to remove all cellular traces whilst maintaining the macro- and micro-architecture of the original tissue. Intestinal tissue engineering has thus far used relatively simple scaffolds that do not replicate the complex architecture of the native organ. The focus of this paper is to describe an efficient decellularization technique for rat small intestine. The isolation of the small intestine so as to ensure the maintenance of a vascular connection is described. The combination of chemical and enzymatic solutions to remove the cells whilst preserving the villus-crypt axis in the luminal aspect of the scaffold is also set out. Finally, assessment of produced scaffolds for appropriate characteristics is discussed.

Human amniotic fluid stem cell differentiation along smooth muscle lineage

Functional smooth muscle engineering requires isolation and expansion of smooth muscle cells (SMCs), and this process is particularly challenging for visceral smooth muscle tissue where progenitor cells have not been clearly identified. Herein we showed for the first time that efficient SMCs can be obtained from human amniotic fluid stem cells (hAFSCs). Clonal lines were generated from c‐kit+ hAFSCs. Differentiation toward SM lineage (SMhAFSCs) was obtained using a medium conditioned by PDGF‐BB and TGF‐β1. Molecular assays revealed higher level of α smooth muscle actin (α‐SMA), desmin, calponin, and smoothelin in SMhAFSCs when compared to hAFSCs. Ultrastructural analysis demonstrated that SMhAFSCs also presented in the cytoplasm increased intermediate filaments, dense bodies, and glycogen deposits like SMCs. SMhAFSC metabolism evaluated via mass spectrometry showed higher glucose oxidation and an enhanced response to mitogenic stimuli in comparison to hAFSCs. Patch clamp of transduced hAFSCs with lentiviral vectors encoding ZsGreen under the control of the α‐SMA promoter was performed demonstrating that SMhAFSCs retained a smooth muscle cell‐like electrophysiological fingerprint. Eventually SMhAFSCs contractility was evident both at single cell level and on a collagen gel. In conclusion, we showed here that hAFSCs under selective culture conditions are able to give rise to functional SMCs.—Ghionzoli, M., Repele, A., Sartiani, L., Costanzi, G., Parenti, A., Spinelli, V., David, A. L., Garriboli, M., Totonelli, G., Tian, J., Andreadis, S. T., Cerbai, E., Mugelli, A., Messineo, A., Pierro, A., Eaton, S., De Coppi, P., Human amniotic fluid stem cell differentiation along smooth muscle lineage. FASEB J. 27, 4853–4865 (2013). www.fasebj.org

High contrast microstructural visualization of natural acellular matrices by means of phase-based x-ray tomography

Acellular scaffolds obtained via decellularization are a key instrument in regenerative medicine both per se and to drive the development of future-generation synthetic scaffolds that could become available off-the-shelf. In this framework, imaging is key to the understanding of the scaffolds’ internal structure as well as their interaction with cells and other organs, including ideally post-implantation. Scaffolds of a wide range of intricate organs (esophagus, lung, liver and small intestine) were imaged with x-ray phase contrast computed tomography (PC-CT). Image quality was sufficiently high to visualize scaffold microarchitecture and to detect major anatomical features, such as the esophageal mucosal-submucosal separation, pulmonary alveoli and intestinal villi. These results are a long-sought step for the field of regenerative medicine; until now, histology and scanning electron microscopy have been the gold standard to study the scaffold structure. However, they are both destructive: hence, they are not suitable for imaging scaffolds prior to transplantation, and have no prospect for post-transplantation use. PC-CT, on the other hand, is non-destructive, 3D and fully quantitative. Importantly, not only do we demonstrate achievement of high image quality at two different synchrotron facilities, but also with commercial x-ray equipment, which makes the method available to any research laboratory.

Long-term cryopreservation of decellularised oesophagi for tissue engineering clinical application

Oesophageal tissue engineering is a therapeutic alternative when oesophageal replacement is required. Decellularised scaffolds are ideal as they are derived from tissue-specific extracellular matrix and are non-immunogenic. However, appropriate preservation may significantly affect scaffold behaviour. Here we aim to prove that an effective method for short- and long-term preservation can be applied to tissue engineered products allowing their translation to clinical application. Rabbit oesophagi were decellularised using the detergent-enzymatic treatment (DET), a combination of deionised water, sodium deoxycholate and DNase-I. Samples were stored in phosphate-buffered saline solution at 4°C (4°C) or slow cooled in medium with 10% Me2SO at -1°C/min followed by storage in liquid nitrogen (SCM). Structural and functional analyses were performed prior to and after 2 and 4 weeks and 3 and 6 months of storage under each condition. Efficient decellularisation was achieved after 2 cycles of DET as determined with histology and DNA quantification, with preservation of the ECM. Only the SCM method, commonly used for cell storage, maintained the architecture and biomechanical properties of the scaffold up to 6 months. On the contrary, 4°C method was effective for short-term storage but led to a progressive distortion and degradation of the tissue architecture at the following time points. Efficient storage allows a timely use of decellularised oesophagi, essential for clinical translation. Here we describe that slow cooling with cryoprotectant solution in liquid nitrogen vapour leads to reliable long-term storage of decellularised oesophageal scaffolds for tissue engineering purposes.

Multicenter retrospective study on management and outcome of newborns affected by surgical necrotizing enterocolitis

BACKGROUND Necrotizing enterocolitis (NEC) is the most common surgical emergency in newborns and it is still a leading cause of death despite the improvements reached in the management of the critically ill neonate. The purpose of this study was to evaluate risk factors, surgical treatments and outcome of surgical NEC. METHODS We retrospectively evaluated a multicentric group of 184 patients with surgical NEC over a period of 5 years (2008-2012). Indications to operation were modified NEC Bell stages IIIA or IIIB. The main outcome was measured in terms of survival and postsurgical complications. RESULTS Data on 184 patients who had a surgical NEC were collected. The majority of patients (153) had a primary laparotomy (83%); 10 patients had peritoneal drainage insertion alone (5%) and 21 patients had peritoneal drainage followed by laparotomy (12%). Overall mortality was 28%. Patients with lower gestational age (P=0.001), lower birth weight (P=0.001), more extensive intestinal involvement (P=0.002) and cardiac diseases (P=0.012) had a significantly higher incidence of mortality. There was no statistically significant association between free abdominal air on the X-ray and mortality (P=0.407). Mortality in the drainage group was 60%, in the laparotomy group and drainage followed by laparotomy group was of 23-24% (P=0.043). There was a high incidence of stenosis (28%) in the drainage group (P=0.002). On multivariable regression, lower birth weight, feeding, bradycardia-desaturation and extent of bowel involvement were independent predictors of mortality. CONCLUSIONS Laparotomy was the most frequent method of treatment (83%). Primary laparotomy and drainage with laparotomy groups had similar mortalities (23-24%), while the drainage alone treatment cohort was associated with the highest mortality (60%) with statistical value (P=0.043). Consequently laparotomy is highly protective in terms of survival rate. Stenosis seemed to be statistically associated with drainage. These findings could discourage the use of peritoneal drainage versus a primary laparotomy whenever the clinical conditions of patients allow this procedure.