Preclinical and clinical orthotopic transplantation of decellularized/engineered tracheal scaffolds: A systematic literature review

Severe tracheal injuries that cannot be managed by mobilization and end-to-end anastomosis represent an unmet clinical need and an urgent challenge to face in surgical practice; within this scenario, decellularized scaffolds (eventually bioengineered) are currently a tempting option among tissue engineered substitutes. The success of a decellularized trachea is expression of a balanced approach in cells removal while preserving the extracellular matrix (ECM) architecture/mechanical properties. Revising the literature, many Authors report about different methods for acellular tracheal ECMs development; however, only few of them verified the devices effectiveness by an orthotopic implant in animal models of disease. To support translational medicine in this field, here we provide a systematic review on studies recurring to decellularized/bioengineered tracheas implantation. After describing the specific methodological aspects, orthotopic implant results are verified. Furtherly, the only three clinical cases of compassionate use of tissue engineered tracheas are reported with a focus on outcomes.

In Vitro Conditioning of Adipose-Derived Mesenchymal Stem Cells by the Endothelial Microenvironment: Modeling Cell Responsiveness towards Non-Genetic Correction of Haemophilia A

In recent decades, the use of adult multipotent stem cells has paved the way for the identification of new therapeutic approaches for the treatment of monogenic diseases such as Haemophilia A. Being already studied for regenerative purposes, adipose-derived mesenchymal stem cells (Ad-MSCs) are still poorly considered for Haemophilia A cell therapy and their capacity to produce coagulation factor VIII (FVIII) after proper stimulation and without resorting to gene transfection. In this work, Ad-MSCs were in vitro conditioned towards the endothelial lineage, considered to be responsible for coagulation factor production. The cells were cultured in an inductive medium enriched with endothelial growth factors for up to 21 days. In addition to significantly responding to the chemotactic endothelial stimuli, the cell populations started to form capillary-like structures and up-regulated the expression of specific endothelial markers (CD34, PDGFRα, VEGFR2, VE-cadherin, CD31, and vWF). A dot blot protein study detected the presence of FVIII in culture media collected from both unstimulated and stimulated Ad-MSCs. Remarkably, the activated partial thromboplastin time test demonstrated that the clot formation was accelerated, and FVIII activity was enhanced when FVIII deficient plasma was mixed with culture media from the untreated/stimulated Ad-MSCs. Overall, the collected evidence supported a possible Ad-MSC contribution to HA correction via specific stimulation by the endothelial microenvironment and without any need for gene transfection.

Growing role of S100B protein as a putative therapeutic target for neurological- and nonneurological-disorders

S100B is a calcium-binding protein mainly expressed by astrocytes, but also localized in other definite neural and extra-neural cell types. While its presence in biological fluids is widely recognized as a reliable biomarker of active injury, growing evidence now indicates that high levels of S100B are suggestive of pathogenic processes in different neural, but also extra-neural, disorders. Indeed, modulation of S100B levels correlates with the occurrence of clinical and/or toxic parameters in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, muscular dystrophy, multiple sclerosis, acute neural injury, inflammatory bowel disease, uveal and retinal disorders, obesity, diabetes and cancer, thus directly linking the levels of S100B to pathogenic mechanisms. In general, deletion/inactivation of the protein causes the improvement of the disease, whereas its over-expression/administration induces a worse clinical presentation. This scenario reasonably proposes S100B as a common therapeutic target for several different disorders, also offering new clues to individuate possible unexpected connections among these diseases.

S100B as a new fecal biomarker of inflammatory bowel diseases

OBJECTIVE

S100 proteins are demonstrated to exert a protective role in the gastrointestinal tract. In the present study, we investigated whether S100B protein, that is typically expressed by enteroglial cells, is detectable in feces and could be a useful noninvasive indicator of gut chronic inflammation.

PATIENTS AND METHODS

This clinical prospective study included n=48 patients suffering Crohn's disease (CD) or ulcerative colitis (UC) and non IBD-controls. The clinical disease activity was evaluated using Harvey-Bradshaw or Mayo Score Index while the diagnosis of IBD was defined based on standard endoscopic and histological criteria. S100B and calprotectin were extracted and analyzed using commercial enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Unlike calprotectin, S100B was significantly decreased in both CD and UC compared to non IBD-patients. The strongest quantitative alterations of S100B were detected concomitantly with signs of active or quiescent disease, including high/normal expression of fecal calprotectin, mucosal damage/cryptitis, mucin depletion and inflammatory infiltrate, as defined by endoscopic evaluation and histological analysis. At the onset of disease and under no Infliximab-based therapy, the lowest was detected suggesting that S100B in feces could have a potential diagnostic value for IBD.

CONCLUSIONS

Testing for S100B and calprotectin could be a useful screening tool to better predict IBD activity.

Serum S100B protein as a marker of severity in Covid-19 patients

SARS-CoV-2 infection shows a wide-ranging clinical severity, requiring prognostic markers. We focused on S100B, a calcium-binding protein present in biological fluids, being a reliable biomarker in disorders having inflammatory processes as common basis and RAGE as main receptor. Since Covid-19 is characterized by a potent inflammatory response also involving RAGE, we tested if S100B serum levels were related to disease severity. Serum samples (n = 74) were collected from hospitalized SARS-CoV-2 positive patients admitted to Covid center. Illness severity was established by admission clinical criteria and Covid risk score. Treatment protocols followed WHO guidelines available at the time. Circulating S100B was determined by ELISA assay. Statistical analysis used Pearson’s χ² test, t-Test, and ANOVA, ANCOVA, Linear Regression. S100B was detected in serum from Covid-19 patients, significantly correlating with disease severity as shown both by the level of intensity of care (p < 0.006) as well by the value of Covid score (Multiple R-squared: 0.3751); the correlation between Covid-Score and S100B was 0.61 (p < 0.01). S100B concentration was associated with inflammation markers (Ferritin, C-Reactive Protein, Procalcitonin), and organ damage markers (Alanine Aminotransferase, Creatinine). Serum S100B plays a role in Covid-19 and can represent a marker of clinical severity in Sars-CoV-2 infected patients.

In Silico Evaluation of Putative S100B Interacting Proteins in Healthy and IBD Gut Microbiota

The crosstalk between human gut microbiota and intestinal wall is essential for the organ’s homeostasis and immune tolerance. The gut microbiota plays a role in healthy and pathological conditions mediated by inflammatory processes or by the gut-brain axes, both involving a possible role for S100B protein as a diffusible cytokine present not only in intestinal mucosa but also in faeces. In order to identify target proteins for a putative interaction between S100B and the microbiota proteome, we developed a bioinformatics workflow by integrating the interaction features of known domains with the proteomics data derived from metataxonomic studies of the gut microbiota from healthy and inflammatory bowel disease (IBD) subjects. On the basis of the microbiota composition, proteins putatively interacting with S100B domains were in fact found, both in healthy subjects and IBD patients, in a reduced number in the latter samples, also exhibiting differences in interacting domains occurrence between the two groups. In addition, differences between ulcerative colitis and Crohn disease samples were observed. These results offer the conceptual framework for where to investigate the role of S100B as a candidate signalling molecule in the microbiota/gut communication machinery, on the basis of interactions differently conditioned by healthy or pathological microbiota.

Negative Pressure From an Internal Spiral Tissue Expander Generates New Subcutaneous Adipose Tissue in an In Vivo Animal Model

BACKGROUND

Tissue expanders are widely utilized in plastic surgery. Traditional expanders usually are "inflatable balloons," which are planned to grow additional skin and/or to create space to be filled, for example, with an implant. In very recent years, reports suggest that negative pressure created by an external device (ie, Brava) induces both skin expansion and adipogenesis.

OBJECTIVES

The authors evaluated and assessed the adipogenetic potential of a novel internal tissue expander in an in vivo animal model.

METHODS

New Zealand female rabbits were enrolled in the study. A prototype spiral inner tissue expander was employed. It consisted of a-dynamic conic expander (DCE) with a valve at the end: when empty, it is flat (Archimedean spiral), whereas when filled with a fluid, it takes a conic shape. Inside the conic spiral, a negative pressure is therefore created. DCE is implanted flat under the latissimus dorsi muscle in experimental animals (rabbit) and then filled to reach the conical shape. Animals were investigated with magnetic resonance imaging, histology, and transmission electronic microscopy at 3, 6, and 12 months.

RESULTS

Magnetic resonance imaging revealed a marked increase in newly formed adipose tissue, reaching its highest amount at 12 months after the DCE implantation. Histology confirmed the existence of new adipocytes, whereas transmission electronic microscopy ultrastructure confirmed that most of these new cells were mature adipocytes.

CONCLUSIONS

Tensile stress, associated with negative-pressure expanders, generated newly white subcutaneous adipose tissue.

Development of Oxidized Polyvinyl Alcohol-Based Nerve Conduits Coupled with the Ciliary Neurotrophic Factor

Functionalized synthetic conduits represent a promising strategy to enhance peripheral nerve regeneration by guiding axon growth while delivering therapeutic neurotrophic factors. In this work, hollow nerve conduits made of polyvinyl alcohol partially oxidized with bromine (OxPVA_Br2) and potassium permanganate (OxPVA_KMnO4) were investigated for their structural/biological properties and ability to absorb/release the ciliary neurotrophic factor (CNTF). Chemical oxidation enhanced water uptake capacity of the polymer, with maximum swelling index of 60.5% ± 2.5%, 71.3% ± 3.6% and 19.5% ± 4.0% for OxPVA_Br2, OxPVA_KMnO4 and PVA, respectively. Accordingly, hydrogel porosity increased from 15.27% ± 1.16% (PVA) to 62.71% ± 8.63% (OxPVA_Br2) or 77.50% ± 3.39% (OxPVA_KMnO4) after oxidation. Besides proving that oxidized PVA conduits exhibited mechanical resistance and a suture holding ability, they did not exert a cytotoxic effect on SH-SY5Y and Schwann cells and biodegraded over time when subjected to enzymatic digestion, functionalization with CNTF was performed. Interestingly, higher amounts of neurotrophic factor were detected in the lumen of OxPVA_Br2 (0.22 ± 0.029 µg) and OxPVA_KMnO4 (0.29 ± 0.033 µg) guides rather than PVA (0.11 ± 0.021 µg) tubular scaffolds. In conclusion, we defined a promising technology to obtain drug delivery conduits based on functionalizable oxidized PVA hydrogels.

Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside

Nowadays, research in Tissue Engineering and Regenerative Medicine is focusing on the identification of instructive scaffolds to address the requirements of both clinicians and patients to achieve prompt and adequate healing in case of injury. Among biomaterials, hemocomponents, and in particular Platelet-rich Fibrin matrices, have aroused widespread interest, acting as delivery platforms for growth factors, cytokines and immune/stem-like cells for immunomodulation; their autologous origin and ready availability are also noteworthy aspects, as safety- and cost-related factors and practical aspects make it possible to shorten surgical interventions. In fact, several authors have focused on the use of Platelet-rich Fibrin in cartilage and tendon tissue engineering, reporting an increasing number of in vitro, pre-clinical and clinical studies. This narrative review attempts to compare the relevant advances in the field, with particular reference being made to the regenerative role of platelet-derived growth factors, as well as the main pre-clinical and clinical research on Platelet-rich Fibrin in chondrogenesis and tenogenesis, thereby providing a basis for critical revision of the topic.

Biofabrication of a novel leukocyte-fibrin-platelet membrane as a cells and growth factors delivery platform for tissue engineering applications

Autologous platelet-rich hemocomponents have emerged as potential biologic tools for regenerative purpose, but their therapeutic efficacy still remains controversial. This work represents the characterization study of an innovative autologous leukocyte-fibrin-platelet membrane (LFPm), which we prepared according to a novel protocol involving multiple cycles of apheresis. The high content in fibrinogen gave to our hemocomponent the appearance of a manipulable and suturable membrane with high elasticity and deformation capacity. Moreover, being highly enriched with platelets, leukocytes, and monocytes/macrophages, the LFPm sustained the local release of bioactive molecules (platelet derived growth factor, vascular endothelial growth factor, interleukin-10, and tumour necrosis factor alpha). In parallel, the evaluation of stemness potential highlighted also that the LFPm contained cells expressing pluripotency and multipotency markers both at the messenger ribonucleic acid (NANOG, SOX2, THY1, NT5E, and ENG) and surface-protein level (CD44^high /CD73⁺ /CD34⁺ /CD117⁺ /CD31⁺ ). Finally, biodegradation analysis interestingly showed a good stability of the membrane for at least 3 weeks in vitro and 1 week in vivo. In both cases, biodegradation was associated with progressive exposure of fibrin scaffold, loss/migration of cellular elements, and release of growth factors. Overall, collected evidence could shed some light on the regenerative effect that LFPms may exert after the autologous implant on a defect site.

Leucocyte and Platelet-rich Fibrin: a carrier of autologous multipotent cells for regenerative medicine

The wound healing is a complex process wherein inflammation, proliferation and regeneration evolve according to a spatio-temporal pattern from the activation of coagulation cascade to the formation of a plug clot including fibrin matrix, blood-borne cells and cytokines/growth factors. Creating environments conducive to tissue repair, the haemoderivatives are commonly proposed for the treatment of hard-to-heal wounds. Here, we explored in vitro the intrinsic regenerative potentialities of a leucocyte- and platelet-rich fibrin product, known as CPL-MB, defining the stemness grade of cells sprouting from the haemoderivative. Using highly concentrated serum-based medium to simulate wound conditions, we isolated fibroblast-like cells (CPL-CMCs) adhering to plastic and showing stable in vitro propagation, heterogeneous stem cell expression pattern, endothelial adhesive properties and immunomodulatory profile. Due to their blood derivation and expression of CXCR4, CPL-CMCs have been suggested to be immature cells circulating in peripheral blood at quiescent state until activation by both coagulation event and inflammatory stimuli such as stromal-derived factor 1/SDF1. Expressing integrins (CD49f, CD103), vascular adhesion molecules (CD106, CD166), endoglin (CD105) and remodelling matrix enzymes (MMP2, MMP9, MMP13), they showed a transendothelial migratory potential besides multipotency. Taken together, our data suggested that a standardized, reliable and economically feasible blood product such as CPL-MB functions as an artificial stem cell niche that, under permissive conditions, originate ex vivo immature cells that could be useful for autologous stem cell-based therapies.

Trophic and neurotrophic factors in human pituitary adenomas (Review)

The pituitary gland is an organ that functionally connects the hypothalamus with the peripheral organs. The pituitary gland is an important regulator of body homeostasis during development, stress, and other processes. Pituitary adenomas are a group of tumors arising from the pituitary gland: they may be subdivided in functional or non-functional, depending on their hormonal activity. Some trophic and neurotrophic factors seem to play a key role in the development and maintenance of the pituitary function and in the regulation of hypothalamo-pituitary-adrenocortical axis activity. Several lines of evidence suggest that trophic and neurotrophic factors may be involved in pituitary function, thus suggesting a possible role of the trophic and neurotrophic factors in the normal development of pituitary gland and in the progression of pituitary adenomas. Additional studies might be necessary to better explain the biological role of these molecules in the development and progression of this type of tumor. In this review, in light of the available literature, data on the following neurotrophic factors are discussed: ciliary neurotrophic factor (CNTF), transforming growth factors β (TGF‑β), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), vascular endothelial growth inhibitor (VEGI), fibroblast growth factors (FGFs) and epidermal growth factor (EGF) which influence the proliferation and growth of pituitary adenomas.

In vivo imaging techniques: a new era for histochemical analysis

In vivo imaging techniques can be integrated with classical histochemistry to create an actual histochemistry of water. In particular, Magnetic Resonance Imaging (MRI), an imaging technique primarily used as diagnostic tool in clinical/preclinical research, has excellent anatomical resolution, unlimited penetration depth and intrinsic soft tissue contrast. Thanks to the technological development, MRI is not only capable to provide morphological information but also and more interestingly functional, biophysical and molecular. In this paper we describe the main features of several advanced imaging techniques, such as MRI microscopy, Magnetic Resonance Spectroscopy, functional MRI, Diffusion Tensor Imaging and MRI with contrast agent as a useful support to classical histochemistry.

Nanopatterned acellular valve conduits drive the commitment of blood-derived multipotent cells

Considerable progress has been made in recent years toward elucidating the correlation among nanoscale topography, mechanical properties, and biological behavior of cardiac valve substitutes. Porcine TriCol scaffolds are promising valve tissue engineering matrices with demonstrated self-repopulation potentiality. In order to define an in vitro model for investigating the influence of extracellular matrix signaling on the growth pattern of colonizing blood-derived cells, we cultured circulating multipotent cells (CMC) on acellular aortic (AVL) and pulmonary (PVL) valve conduits prepared with TriCol method and under no-flow condition. Isolated by our group from Vietnamese pigs before heart valve prosthetic implantation, porcine CMC revealed high proliferative abilities, three-lineage differentiative potential, and distinct hematopoietic/endothelial and mesenchymal properties. Their interaction with valve extracellular matrix nanostructures boosted differential messenger RNA expression pattern and morphologic features on AVL compared to PVL, while promoting on both matrices the commitment to valvular and endothelial cell-like phenotypes. Based on their origin from peripheral blood, porcine CMC are hypothesized in vivo to exert a pivotal role to homeostatically replenish valve cells and contribute to hetero- or allograft colonization. Furthermore, due to their high responsivity to extracellular matrix nanostructure signaling, porcine CMC could be useful for a preliminary evaluation of heart valve prosthetic functionality.

In vitro assessment of TAT - Ciliary Neurotrophic Factor therapeutic potential for peripheral nerve regeneration

In regenerative neurobiology, Ciliary Neurotrophic Factor (CNTF) is raising high interest as a multifunctional neurocytokine, playing a key role in the regeneration of injured peripheral nerves. Despite its promising trophic and regulatory activity, its clinical application is limited by the onset of severe side effects, due to the lack of efficient intracellular trafficking after administration. In this study, recombinant CNTF linked to the transactivator transduction domain (TAT) was investigated in vitro and found to be an optimized fusion protein which preserves neurotrophic activity, besides enhancing cellular uptake for therapeutic advantage. Moreover, a compelling protein delivery method was defined, in the future perspective of improving nerve regeneration strategies. Following determination of TAT-CNTF molecular weight and concentration, its specific effect on neural SH-SY5Y and PC12 cultures was assessed. Cell proliferation assay demonstrated that the fusion protein triggers PC12 cell growth within 6h of stimulation. At the same time, the activation of signal transduction pathway and enhancement of cellular trafficking were found to be accomplished in both neural cell lines after specific treatment with TAT-CNTF. Finally, the recombinant growth factor was successfully loaded on oxidized polyvinyl alcohol (PVA) scaffolds, and more efficiently released when polymer oxidation rate increased. Taken together, our results highlight that the TAT domain addiction to the protein sequence preserves CNTF specific neurotrophic activity in vitro, besides improving cellular uptake. Moreover, oxidized PVA could represent an ideal biomaterial for the development of nerve conduits loaded with the fusion protein to be delivered to the site of nerve injury.

Neuronal commitment of human circulating multipotent cells by carbon nanotube-polymer scaffolds and biomimetic peptides

AIM

We aimed to set up a self-standing, biomimetic scaffold system able to induce and support per se neuronal differentiation of autologous multipotent cells.

MATERIALS & METHODS

We isolated a population of human circulating multipotent cells (hCMCs), and used carbon nanotube/polymer nanocomposite scaffolds to mimic electrical/nanotopographical features of the neural environment, and biomimetic peptides reproducing axon guidance cues from neural proteins.

RESULTS

hCMCs showed high degree of stemness and multidifferentiative potential; stimuli from the scaffolds and biomimetic peptides could induce and boost hCMC differentiation toward neuronal lineage despite the absence of exogenously added, specific growth factors.

CONCLUSION

This work suggests the scaffold-peptides system combined with autologous hCMCs as a functional biomimetic, self-standing prototype for neural regenerative medicine applications.

Autologous chondrocytes as a novel source for neo-chondrogenesis in haemophiliacs

Haemophilic arthropathy is the major cause of disability in patients with haemophilia and, despite prophylaxis with coagulation factor concentrates, some patients still develop articular complications. We evaluate the feasibility of a tissue engineering approach to improve current clinical strategies for cartilage regeneration in haemophiliacs by using autologous chondrocytes (haemophilic chondrocytes; HaeCs). Little is known about articular chondrocytes from haemophilic patients and no characterisation has as yet been performed. An investigation into whether blood exposure alters HaeCs should be interesting from the perspective of autologous implants. The typical morphology and expression of specific target genes and surface markers were therefore assessed by optical microscopy, reverse transcription plus the polymerase chain reaction (PCR), real-time PCR and flow-cytometry. We then considered chondrocyte behaviour on a bio-hybrid scaffold (based on polyvinyl alcohol/Wharton's jelly) as an in vitro model of articular cartilage prosthesis. Articular chondrocytes from non-haemophilic donors were used as controls. HaeC morphology and the resulting immunophenotype CD44(+)/CD49c(+)/CD49e(+)/CD151(+)/CD73(+)/CD49f(-)/CD26(-) resembled those of healthy donors. Moreover, HaeCs were active in the transcription of genes involved in the synthesis of the extracellular matrix proteins of the articular cartilage (ACAN, COL1A, COL2A, COL10A, COL9A, COMP, HAS1, SOX9), although the over-expression of COL1A1, COL10A1, COMP and HAS was observed. In parallel, the composite scaffold showed adequate mechanical and biological properties for cartilage tissue engineering, promoting chondrocyte proliferation. Our preliminary evidence contributes to the characterisation of HaeCs, highlighting the opportunity of using them for autologous cartilage implants in patients with haemophilia.

Fluorescence-based gene reporter plasmid to track canonical Wnt signaling in ENS inflammation

In several gut inflammatory or cancer diseases, cell-cell interactions are compromised, and an increased cytoplasmic expression of β-catenin is observed. Over the last decade, numerous studies provided compelling experimental evidence that the loss of cadherin-mediated cell adhesion can promote β-catenin release and signaling without any specific activation of the canonical Wnt pathway. In the present work, we took advantage of the ability of lipofectamine-like reagent to cause a synchronous dissociation of adherent junctions in cells isolated from the rat enteric nervous system (ENS) for obtaining an in vitro model of deregulated β-catenin signaling. Under these experimental conditions, a green fluorescent protein Wnt reporter plasmid called ΔTop_EGFP3a was successfully tested to screen β-catenin stabilization at resting and primed conditions with exogenous Wnt3a or lipopolysaccharide (LPS). ΔTop_EGFP3a provided a reliable and strong fluorescent signal that was easily measurable and at the same time highly sensitive to modulations of Wnt signaling following Wnt3a and LPS stimulation. The reporter gene was useful to demonstrate that Wnt3a exerts a protective activity in the ENS from overstimulated Wnt signaling by promoting a downregulation of the total β-catenin level. Based on this evidence, the use of ΔTop_EGFP3a reporter plasmid could represent a more reliable tool for the investigation of Wnt and cross-talking pathways in ENS inflammation.

Partially oxidized polyvinyl alcohol as a promising material for tissue engineering

The desired clinical outcome after implantation of engineered tissue substitutes depends strictly on the development of biodegradable scaffolds. In this study we fabricated 1% and 2% oxidized polyvinyl alcohol (PVA) hydrogels, which were considered for the first time for tissue-engineering applications. The final aim was to promote the protein release capacity and biodegradation rate of the resulting scaffolds in comparison with neat PVA. After physical crosslinking, characterization of specific properties of 1% and 2% oxidized PVA was performed. We demonstrated that mechanical properties, hydrodynamic radius of molecules, thermal characteristics and degree of crystallinity were inversely proportional to the PVA oxidation rate. On the other hand, swelling behaviour and protein release were enhanced, confirming the potential of oxidized PVA as a protein delivery system, besides being highly biodegradable. Twelve weeks after in vivo implantation in mice, the modified hydrogels did not elicit severe inflammatory reactions, showing them to be biocompatible and to degrade faster as the degree of oxidation increased. According to our results, oxidized PVA stands out as a novel biomaterial for tissue engineering that can be used to realize scaffolds with customizable mechanical behaviour, protein-loading ability and biodegradability. Copyright © 2015 John Wiley & Sons, Ltd.

Umbilical cord mesenchymal stem cells modulate dextran sulfate sodium induced acute colitis in immunodeficient mice

Introduction

Inflammatory bowel diseases (IBD) are complex multi-factorial diseases with increasing incidence worldwide but their treatment is far from satisfactory. Unconventional strategies have consequently been investigated, proposing the use of cells as an effective alternative approach to IBD. In the present study we examined the protective potential of exogenously administered human umbilical cord derived mesenchymal stem cells (UCMSCs) against Dextran Sulfate Sodium (DSS) induced acute colitis in immunodeficient NOD.CB₁₇-Prkdc^scid/J mice with particular attention to endoplasmic reticulum (ER) stress.

Methods

UCMSCs were injected in NOD.CB₁₇-Prkdc^scid/J via the tail vein at day 1 and 4 after DSS administration. To verify attenuation of DSS induced damage by UCMSCs, Disease Activity Index (DAI) and body weight changes was monitored daily. Moreover, colon length, histological changes, myeloperoxidase and catalase activities, metalloproteinase (MMP) 2 and 9 expression and endoplasmic reticulum (ER) stress related proteins were evaluated on day 7.

Results

UCMSCs administration to immunodeficient NOD.CB₁₇-Prkdc^scid/J mice after DSS damage significantly reduced DAI (1.45 ± 0.16 vs 2.08 ± 0.18, p < 0.05), attenuating the presence of bloody stools, weight loss, colon shortening (8.95 ± 0.33 cm vs 6.8 ± 0.20 cm, p < 0.01) and histological score (1.97 ± 0.13 vs 3.27 ± 0.13, p < 0.001). Decrease in neutrophil infiltration was evident from lower MPO levels (78.2 ± 9.7 vs 168.9 ± 18.2 U/g, p < 0.01). DSS treatment enhanced MMP2 and MMP9 activities (>3-fold), which were significantly reduced in mice receiving UCMSCs. Moreover, positive modulation in ER stress related proteins was observed after UCMSCs administration.

Conclusions

Our results demonstrated that UCMSCs are able to prevent DSS-induced colitis in immunodeficient mice. Using these mice we demonstrated that our UCMSCs have a direct preventive effect other than the T-cell immunomodulatory properties which are already known. Moreover we demonstrated a key function of MMPs and ER stress in the establishment of colitis suggesting them to be potential therapeutic targets in IBD treatment.

Poly-ε-caprolactone composite scaffolds for bone repair

Synthetic biomaterials combined with cells and osteogenic factors represent a promising approach for the treatment of a number of orthopedic diseases, such as bone trauma and congenital malformations. To guarantee optimal biological properties, bone substitutes are prepared with a 3D structure and porosity grade functional to drive cell migration and proliferation, diffusion of factors, vascularization and cell waste expulsion. In this study, synthetic hydroxyapatite (HA) or rat bone extracellular matrix (BP) were examined in an effort to optimize the mechanical properties and osteogenic activity of poly-ε-caprolactone scaffolds prepared with alginate threads (PCL-AT). Using rabbit bone marrow-derived mesenchymal stem cells (rMSCs), the effects of PCL composite substrates on cell adhesion, growth and osteogenic differentiation were evaluated. Micro-CT analysis and scanning electron microscopy evidenced that porous PCL scaffolds containing HA or BP acquire a trabecular bone-like structure with interconnected pores homogenously distributed and are characterized by a pore diameter of approximately 10 µm (PCL-AT-BP) or ranging from 10 to 100 µm. Although the porosity grade of both PCL-AT-HA and PCL-AT-BP promoted optimal conditions for the cell growth of rMSCs at the early phase, the presence of BP was crucial to prolong the cell viability at the late phase. Moreover, a precocious expression of Runx2 (at 7 days) was observed in PCL-AT-BP in combination with osteogenic soluble factors suggesting that BP controls better than HA the osteogenic maturation process in bone substitutes.

Evaluation of vascular grafts based on polyvinyl alcohol cryogels

The present study designed and developed blood vessel substitutes (BVSs) composed of polyvinyl alcohol (PVA) cryogels. The in vitro results demonstrated that the coating of the polymer with lyophilized decellularized vascular matrix (DVM) greatly enhanced the adhesion of human umbilical vein endothelial cells (HUVECs). However, when PVA̸DVM BVSs were implanted into the abdominal aorta of Sprague‑Dawley rats, DVM was identified as a highly thrombogenic surface resulting in the mortality of all animals 3‑4 days after surgery. By contrast, all rats implanted with PVA survived and were sacrificed after 12 months. The luminal surface of the explanted grafts was completely covered by endothelial cells and the inner diameter was similar to that of the original vessel. In conclusion, the present study indicated that PVA may be considered as a promising biomaterial for the fabrication of artificial vessels.

Maintenance of the enteric stem cell niche by bacterial lipopolysaccharides? Evidence and perspectives

The enteric nervous system (ENS) has to respond to continuously changing microenvironmental challenges within the gut and is therefore dependent on a neural stem cell niche to keep the ENS functional throughout life. In this study, we hypothesize that this stem cell niche is also affected during inflammation and therefore investigated lipopolysaccharides (LPS) effects on enteric neural stem/progenitor cells (NSPCs). NSPCs were derived from the ENS and cultured under the influence of different LPS concentrations. LPS effects upon proliferation and differentiation of enteric NSPC cultures were assessed using immunochemistry, flow cytometry, western blot, Multiplex ELISA and real-time PCR. LPS enhances the proliferation of enteric NSPCs in a dose-dependent manner. It delays and modifies the differentiation of these cells. The expression of the LPS receptor toll-like receptor 4 on NSPCs could be demonstrated. Moreover, LPS induces the secretion of several cytokines. Flow cytometry data gives evidence for individual subgroups within the NSPC population. ENS-derived NSPCs respond to LPS in maintaining at least partially their stem cell character. In the case of inflammatory disease or trauma where the liberation and exposure to LPS will be increased, the expansion of NSPCs could be a first step towards regeneration of the ENS. The reduced and altered differentiation, as well as the induction of cytokine signalling, demonstrates that the stem cell niche may take part in the LPS-transmitted inflammatory processes in a direct and defined way.

In vitro biological activity of bovine milk ribonuclease-4

Several members of the ribonuclease superfamily possess a variety of interesting biological properties, including ribonucleolytic, angiogenic, antiproliferative, cytotoxic, embryotoxic, aspermatogenic and antitumoral activity. In this study, we report the purification from bovine milk of a protein with structural and enzymatic properties very similar to those of ribonuclease-4 (RNase-4), which is normally present in the liver and lungs, and examined its functional properties, biological activity and cytotoxic effects. RNase-4, at physiological concentrations, had a positive effect on the vitality and proliferation of human umbilical vein endothelial cells. Moreover, it induced an increase in cellular migration and the formation of in vitro capillary-like structures. We also evaluated the effect of RNase-4 in vitro on human breast, colorectal and cervical carcinoma cell lines. The protein was revealed to have a cytotoxic effect similar to that of RNase-A. We suggest that the positive effects of RNase-4 on normal cells were due to its particularly close interaction with RNase inhibitor, while good conformational stability and resistance to proteolytic degradation potentially favour ribonuclease cytotoxicity.

Assessment of in vitro temporal corrosion and cytotoxicity of AZ91D alloy

Magnesium alloys represent a valuable option for the production of bioresorbable implantable medical devices aimed to improve the therapeutic approach and minimize the potential risks related to biostable materials. In this regard, the degradation process needs to be carefully evaluated in order to assess the effectiveness of the regenerative support and the eventual toxic effects induced by the released corrosion products. Aluminium is one of the most common alloying element that raised several safety concerns, contributing to shift the investigation toward Al-free alloys. To delve into this issue, a long-term investigation (up to 28 days) was performed using AZ91D alloy, due to its relevant Al content. Immersion tests in phosphate buffered saline (PBS) solution was performed following the ASTM standards and the corrosion behaviour was evaluated at fixed time points by means of electrochemical techniques. Cytotoxic effects were assessed by culturing human neuroblastoma cells with conditioned medium derived from immersion tests at different dilution degree. An increase in the resistance corrosion with the time was observed. In all the investigated cases the presence of Al in the conditioned media did not induce significant toxic effects directly correlated to its content. A decrease of cell viability was only observed in the case of 50 % dilution of PBS conditioned for the longest immersion period (i.e., 28 days).

In vitro evaluation of TAT-OP1 osteogenic properties and prospects for in vivo applications

So far, osteogenic protein 1 (OP1) is biotechnologically produced and approved for the treatment of human lumbar spine fusion and long bone non-union fractures. When combined with the TAT sequence, it has been demonstrated in vitro to be easily taken up by PC12 neuronal cells and to acquire its biological activity after intracellular refolding. In this study, TAT-OP1 was shown to be a useful strategy to efficiently drive denatured OP1 into mouse MC3T3E1 pre-osteoblasts. The correct in vitro protein refolding was verified by the activation of the BMP cascade, while the osteogenic potential of OP1 was demonstrated by increased expression of alkaline phosphatase, osteonectin and osteocalcin.

Systemic administration of a novel human umbilical cord mesenchymal stem cells population accelerates the resolution of acute liver injury

BACKGROUND

Hepatocytes and stem cells transplantation may be an alternative to liver transplantation in acute or chronic liver disease. We aimed to evaluate the therapeutic potential of mesenchymal stem cells from human umbilical cord (UCMSCs), a readily available source of mesenchymal stem cells, in the CCl4-induced acute liver injury model.

METHODS

Mesenchymal stem cells profile was analyzed by flow cytometry. In order to evaluate the capability of our UCMSCs to differentiate in hepatocytes, cells were seeded on three different supports, untreated plastic support, MatrigelTM and human liver acellular matrix. Cells were analyzed by immunocitochemistry for alpha-fetoprotein and albumin expression, qPCR for hepatocyte markers gene expression, Periodic Acid-Schiff staining for glycogen storage, ELISA for albumin detection and colorimetric assay for urea secretion.To assess the effects of undifferentiated UCMSCs in hepatic regeneration after an acute liver injury, we transplanted them via tail vein in mice injected intraperitoneally with a single dose of CCl4. Livers were analyzed by histological evaluation for damage quantification, immunostaining for Kupffer and stellate cells/liver myofibroblasts activation and for UCMSCs homing. Pro- and anti-inflammatory cytokines gene expression was evaluated by qPCR analysis and antioxidant enzyme activity was measured by catalase quantification.Data were analyzed by Mann-Whitney U-test, Kruskal-Wallis test and Cuzick's test followed by Bonferroni correction for multiple comparisons.

RESULTS

We have standardized the isolation procedure to obtain a cell population with hepatogenic properties prior to in vivo transplantation. When subjected to hepatogenic differentiation on untreated plastic support, UCMSCs differentiated in hepatocyte-like cells as demonstrated by their morphology, progressive up-regulation of mature hepatocyte markers, glycogen storage, albumin and urea secretion. However, cells seeded on 3D-supports showed a minor or negligible differentiation capacity.UCMSCs-transplanted mice showed a more rapid damage resolution, as shown by histological analysis, with a lower inflammation level and an increased catalase activity compared to CCl4-treated mice.

CONCLUSIONS

Our findings show that UCMSCs can be reliably isolated, have hepatogenic properties and following systemic administration are able to accelerate the resolution of an acute liver injury without any differentiation and manipulation. These features make UCMSCs strong candidates for future application in regenerative medicine for human acute liver disease.

Ratiometric detection of Cr3+ and Hg2+ by a naphthalimide-rhodamine based fluorescent probe

Newly synthesized rhodamine derivatives, L(1) and L(2), are found to bind specifically to Hg(2+) or Cr(3+) in presence of large excess of other competing ions with associated changes in their optical and fluorescence spectral behavior. These spectral changes are significant enough in the visible region of the spectrum and thus, allow the visual detection. For L(1), the detection limit is even lower than the permissible [Cr(3+)] or [Hg(2+)] in drinking water as per standard U.S. EPA norms; while the receptor, L2 could be used as a ratiometric sensor for detection of Cr(3+) and Hg(2+) based on the resonance energy transfer (RET) process involving the donor naphthalimide and the acceptor Cr(3+)/Hg(2+)-bound xanthene fragment. Studies reveal that these two reagents could be used for recognition and sensing of Hg(2+)/Cr(3+). Further, confocal laser microscopic studies confirmed that the reagent L(2) could also be used as an imaging probe for detection of uptake of these ions in A431 cells.

Involvement of rat hippocampal astrocytes in β-amyloid-induced angiogenesis and neuroinflammation

Although Alzheimer's disease (AD) is considered a neurodengenerative disorders, in the last few years a large amount of evidence has suggested that it is also a vascular pathology characterized by increased capillary density and expression of angiogenic factors. In AD the endothelium degenerates, promoting local neuroinflammation and activation of brain endothelium, perivascular microglia, pericytes, astrocytes. Excess tumor necrosis factor (TNF) in the cerebrospinal fluid (CSF), at a concentration of 25 times higher than in the control group, has been demonstrated in AD. Recent studies provide evidence that treatment with TNF-α antagonists may result in a rapid cognitive improvement in AD patients. In the present work we investigated the role of astrocytes in AD angiogenesis and neuroinflammation by means of conditioned media of untreated and Aβ-treated rat hippocampal astrocytes (RHAs) on rat microvascular endothelial cells (RCECs). The results demonstrated that RHA media increase RCEC proliferation and capillary-like structure formation. Moreover RHAs secrete IL-1β and, only after the Aβ1-42 treatment, TNF-α promotes RCEC release of IL-1β, IL-6 and TNF-α. The removal of IL-1β, TNF-α and/or VEGF, a strong angiogenic inducer highly over-expressed in AD brains, by means of specific antibody-coated beads in RHA media affects RCEC release of IL-1β, IL-6 and TNF-α. We hypothesised that astrocytes contribute to AD angiogenesis and neuroinflammation by the direct release of pro-inflammatory cytokines. The effect of an anti-inflammatory agent, such as etanercept, decreased RCEC in vitro cytokine release. This could be compared to the effect found in our experiments with antibody anti TNF-α-coated beads.

Decellularized bovine reinforced vessels for small-diameter tissue-engineered vascular grafts

The aim of the present study was to investigate the influence of a decellularization protocol on the structure and the mechanical behavior of small-diameter (<6 mm) tibial calf arteries and veins. Calf vessels were decellularized by a detergent-enzymatic method (DEM), partially hydrolyzed with trypsin and subsequently cross-linked using poly(ethylene glycol) diglycidyl ether. Our results showed that i) the DEM can be considered a simple and valuable procedure for the preparation of complete acellular arteries and veins able to preserve a high degree of collagen and elastic fibers, and ii) poly(ethylene glycol) diglycidyl ether cross-linking treatment provides appropriate mechanical reinforcement of blood vessels. Histologically, the decellularized vessels were obtained employing the detergent-enzymatic procedure and their native extracellular matrix histoarchitecture and components remained well preserved. Moreover, the decellularization protocol can be considered an effective method to remove HLA class I antigen expression from small-diameter tibial calf arteries and veins. Cytocompatibility of decellularized cross-linked vessels was evaluated by endothelial and smooth muscle cell seeding on luminal and adventitial vessel surfaces, respectively.

Porous alginate/poly(ε-caprolactone) scaffolds: preparation, characterization and in vitro biological activity

In bone tissue engineering, scaffolds with controlled porosity are required to allow cell ingrowth, nutrient diffusion and sufficient formation of vascular networks. The physical properties of synthetic scaffolds are known to be dependent on the biomaterial type and its processing technique. In this study, we demonstrate that the separation phase technique is a useful method to process poly(ε-caprolactone) (PCL) into a desired shape and size. Moreover, using poly(ethylene glycol), sucrose, fructose and Ca2+ alginate as porogen agents, we obtained PCL scaffolds with three-dimensional porous structures characterized by different pore size and geometry. Scanning electron microscopy and porosity analysis indicated that PCL scaffolds prepared with Ca2+ alginate threads resemble the porosity and the homogeneous pore size distribution of native bone. In parallel, MicroCT analysis confirmed the presence of interconnected void spaces suitable to guarantee a biological environment for cellular growth, as demonstrated by a biocompatibility test with MC3T3-E1 murine preosteoblastic cells. In particular, scaffolds prepared with Ca2+ alginate threads increased adhesion and proliferation of MC3T3-E1 cells under basal culture conditions, and upon stimulation with a specific differentiation culture medium they enhanced the early and later differentiated cell functions, including alkaline phosphatase activity and mineralized extracellular matrix production. These results suggest that PCL scaffolds, obtained by separation phase technique and prepared with alginate threads, could be considered as candidates for bone tissue engineering applications, possessing the required physical and biological properties.

Synthesis, in vitro and in vivo preliminary evaluation of anti-angiogenic properties of some pyrroloazaflavones

This work investigated the in vitro and in vivo anti-angiogenic activity of some pyrroloazaflavones, exactly 2-phenyl-1H-pyrrolo[2,3-h]quinolin-4(7H)ones, with vinblastine as reference compound. Growth inhibitory activity, migration, and capillary-like structures formation were determined in human umbilical vein endothelial cell cultures, and Matrigel plug assay was carried out to evaluate in vivo effects on angiogenesis. Collectively, our results indicate that some pyrroloazaflavone derivatives, at non-cytotoxic concentrations and like vinblastine are able: (i) to exert in vitro anti-angiogenic activity and (ii) to counteract in vitro and in vivo the pro-angiogenic effects of fibroblast growth factor-2 (FGF-2).

Recombinant human TAT-OP1 to enhance NGF neurogenic potential: preliminary studies on PC12 cells

Osteogenic protein 1 (OP1), also known as bone morphogenic protein-7 (BMP7), is a multifunctional cytokine with demonstrated neurogenic potential. As the recombinant OP1 (rhOP1) was shown to provide axonal guidance cues and to prevent the reduction of dendritic growth in the injury-induced cortical cultures, it was suggested that an in vivo efficient rhOP1 delivery could enhance neurite growth and functional reconnectivity in the damaged brain. In the present work, we engineered a chimeric molecule in which rhBMP7 was fused to a protein transduction domain derived from HIV-1 TAT protein to deliver the denatured recombinant BMP7 into cells and obtain its chaperone-mediated folding, circumventing the expensive and not much efficient in vitro refolding procedures. When tested on rat PC12 cells, a widely used in vitro neurogenic differentiation model, the resulting fusion protein (rhTAT-OP1) demonstrated to enter fastly into the cells, lose HIV-TAT sequence and interact with membrane receptors activating BMP pathway by SMAD 1/5/8 phosphorylation. In comparison with nerve growth factor (NGF) and BMP7, it proved itself effective to induce the formation of more organized H and M neurofilaments. Moreover, if used in combination with NGF, it stimulated a significant (P < 0.05) and more precocious dendritic outgrowth with respect to NGF alone. These results indicate that rhTAT-OP1 fused with TAT transduction domain shows neurogenic activity and may be a promising enhancer factor in NGF-based therapies.

Micropatterned three-dimensional hydrogel system to study human endothelial-mesenchymal stem cell interactions

The creation of vascularized engineered tissues of clinically relevant size is a major challenge of tissue engineering. While it is known that endothelial and mural vascular cells are integral to the formation of stable blood vessels, the specific cell types and optimal conditions for engineered vascular networks are poorly understood. To this end, we investigated the vasculogenic potential of human mesenchymal stem cell (MSC) populations derived from three different sources: (a) bone marrow aspirates; (b) perivascular cells from the umbilical cord vein; and (c) perivascular cells from the umbilical cord artery. Cell populations were isolated and identified as MSCs according to their phenotypes and differentiation potential. Human umbilical vein endothelial cells (HUVECs) were used as a standard for endothelial cells. A novel co-culture system was developed to study cell-cell interactions in a spatially controlled three-dimensional (3D) fibrin hydrogel model. Using microfluidic patterning, it was possible to localize hydrogel-encapsulated HUVECs and MSCs within separate channels spaced at 500, 1000 or 2000 microm. All three MSC populations had similar expression profiles of mesenchymal cell markers and similar capacity for osteogenic and adipogenic differentiation. However, bone marrow-derived MSCs (but not umbilical vein or artery derived MSCs) showed strong distance-dependent migration toward HUVECs and supported the formation of stable vascular networks resembling capillary-like vasculature. The presented approach provides a simple and robust model to study the cell-cell communication of relevance to engineering vascularized tissues.

Pancreatic acellular matrix supports islet survival and function in a synthetic tubular device: in vitro and in vivo studies

Increasing pancreatic islet survival and function is a starting point for obtaining a valuable bioartificial pancreas for the treatment of type 1 diabetes. In this context, decellularized matrices, obtained after the removal of tissue cellular part, are known to support in vitro adhesion, growth, and function of several cell types. We demonstrate that a homologous acellular pancreatic matrix is a suitable scaffold for rat islet cultures maintaining their long-term viability and function. Islets adhered to the pancreatic matrix showed a constant glucose-induced insulin release during long-term in vitro incubation, while islets cultured without a matrix or on the liver matrix showed a progressive reduction. In order to obtain implantable devices, acellular matrix/islet cultures were entrapped into poly(vinyl alcohol) (PVA)/ poly(ethylene glycol) (PEG) tubes obtained by the freezing/thawing procedure. Under this condition, an in vitro constant insulin release was detected. The devices were then implanted into diabetic rats where reduced insulin requirement was noted suggesting insulin secretory activity of islets contained in the device. Indeed, immunofluorescence confirmed the presence of insulin- and glucagon-producing cells into the explanted devices. These data show that PVA/PEG semi-permeable membrane can obtain devices that restore, at least in part, insulin secretion.

Middle-term expansion of hematopoietic cord blood cells with new human stromal cell line feeder-layers and different cytokine cocktails

Cord blood (CB) is a source of hematopoietic stem cells (HSCs) and is an alternative to bone marrow for allogenic transplantation in patients with hematological disorders. The improvement of HSC in vitro expansion is one of the main challenges in cell therapy. Stromal components and soluble factors, such as cytokines, can be useful to induce in vitro cell expansion. Hence, we investigated whether feeder-layers from new stromal cell lines and different exogenous cytokine cocktails induce HSC expansion in middle-term cultures. CB HSC middle-term expansion was carried out in co-cultures on different feeder-layers exposed to three different cytokine cocktails. CB HSC expansion was also carried out in stroma-free cultures in the presence of different cytokine cocktails. Clonogenic tests were performed, and cell growth levels were evaluated. Moreover, the presence of VCAM-1 mRNA was assessed, and the mesenchymal cell-like phenotype expression was detected. All feeder-layers were able to induce a significant clonogenic growth with respect to the control culture, and all of the cytokine cocktails induced a significant increase in CB cell expansion indexes, even though no potential variation dependent on their composition was noted. The modulative effects of the different cocktails, exerted on each cell line used, was dependent on their composition. Finally, all cell lines were positive for CD73, CD117 and CD309, similar to mesenchymal stem cells present in adult bone marrow and in other human tissues, and negative for the hematopoietic markers. These data indicate that our cell lines have, not only a stromal cell-like phenotype, but also a mesenchymal cell-like phenotype, and they have the potential to support in vitro expansion of CB HSCs. Moreover, exogenous cytokines can be used in synergism with feeder-layers to improve the expansion levels of CB HSCs in preparation for their clinical use in allogenic transplantation.

Involvement of the receptor for advanced glycation-end products (RAGE) in beta-amyloid-induced toxic effects in rat cerebromicrovascular endothelial cells cultured in vitro

To ascertain whether the potential biological effects of beta amyloid (betaA) on the endothelium are partly mediated by the receptor for advanced glycation-end products (RAGE), we performed a series of experiments which analyzed the effects of the betaA(1-42) peptide on in vitro cerebromicrovascular endothelial cells (CECs). Our results suggest that RAGE is directly responsible for betaA(1-42) actions on CECs, such as its toxic effect on cell survival, viability and angiogenic capability. We observed that a 6-h incubation period exposing CECs to betaA(1-42) increased the extracellular levels of nitrite. Furthermore, the presence of a nitric oxide synthase inhibitor, L-NAME, was able to enhance CEC survival and viability. Immunocytochemical analyses demonstrated that the peptide induced expression of the inducible form of NOS, iNOS, typically synthesized in response to immune/inflammatory stimuli. Upon blocking the interaction of betaA(1-42) and RAGE, we observed significantly decreased levels of NO and suppression of iNOS immunoreactivity. In conclusion, our data suggest the involvement of RAGE, at least partly, in mediating the effects of betaA(1-42) on CECs. In particular, the decrease of in vitro cell viability and functionality and nitrosative stress activation was inhibited by blocking betaA(1-42)-RAGE interaction.

A double-chamber rotating bioreactor for the development of tissue-engineered hollow organs: from concept to clinical trial

Cell and tissue engineering are now being translated into clinical organ replacement, offering alternatives to fight morbidity, organ shortages and ethico-social problems associated with allotransplantation. Central to the recent first successful use of stem cells to create an organ replacement in man was our development of a bioreactor environment. Critical design features were the abilities to drive the growth of two different cell types, to support 3D maturation, to maintain biomechanical and biological properties and to provide appropriate hydrodynamic stimuli and adequate mass transport. An analytical model was developed and applied to predict oxygen profiles in the bioreactor-cultured organ construct and in the culture media, comparing representative culture configurations and operating conditions. Autologous respiratory epithelial cells and mesenchymal stem cells (BMSCs, then differentiated into chondrocytes) were isolated, characterized and expanded. Both cell types were seeded and cultured onto a decellularized human donor tracheal matrix within the bioreactor. One year post-operatively, graft and patient are healthy, and biopsies confirm angiogenesis, viable epithelial cells and chondrocytes. Our rotating double-chamber bioreactor permits the efficient repopulation of a decellularized human matrix, a concept that can be applied clinically, as demonstrated by the successful tracheal transplantation.

miR-17 family of microRNAs controls FGF10-mediated embryonic lung epithelial branching morphogenesis through MAPK14 and STAT3 regulation of E-Cadherin distribution

The miR-17 family of microRNAs has recently been recognized for its importance during lung development. The transgenic overexpression of the entire miR-17-92 cluster in the lung epithelium led to elevated cellular proliferation and inhibition of differentiation, while targeted deletion of miR-17-92 and miR-106b-25 clusters showed embryonic or early post-natal lethality. Herein we demonstrate that miR-17 and its paralogs, miR-20a, and miR-106b, are highly expressed during the pseudoglandular stage and identify their critical functional role during embryonic lung development. Simultaneous downregulation of these three miRNAs in explants of isolated lung epithelium altered FGF10 induced budding morphogenesis, an effect that was rescued by synthetic miR-17. E-Cadherin levels were reduced, and its distribution was altered by miR-17, miR-20a and miR-106b downregulation, while conversely, beta-catenin activity was augmented, and expression of its downstream targets, including Bmp4 as well as Fgfr2b, increased. Finally, we identified Stat3 and Mapk14 as key direct targets of miR-17, miR-20a, and miR-106b and showed that simultaneous overexpression of Stat3 and Mapk14 mimics the alteration of E-Cadherin distribution observed after miR-17, miR-20a, and miR-106b downregulation. We conclude that the mir-17 family of miRNA modulates FGF10-FGFR2b downstream signaling by specifically targeting Stat3 and Mapk14, hence regulating E-Cadherin expression, which in turn modulates epithelial bud morphogenesis in response to FGF10 signaling.

Clinical transplantation of a tissue-engineered airway

BACKGROUND

The loss of a normal airway is devastating. Attempts to replace large airways have met with serious problems. Prerequisites for a tissue-engineered replacement are a suitable matrix, cells, ideal mechanical properties, and the absence of antigenicity. We aimed to bioengineer tubular tracheal matrices, using a tissue-engineering protocol, and to assess the application of this technology in a patient with end-stage airway disease.

METHODS

We removed cells and MHC antigens from a human donor trachea, which was then readily colonised by epithelial cells and mesenchymal stem-cell-derived chondrocytes that had been cultured from cells taken from the recipient (a 30-year old woman with end-stage bronchomalacia). This graft was then used to replace the recipient's left main bronchus.

FINDINGS

The graft immediately provided the recipient with a functional airway, improved her quality of life, and had a normal appearance and mechanical properties at 4 months. The patient had no anti-donor antibodies and was not on immunosuppressive drugs.

INTERPRETATION

The results show that we can produce a cellular, tissue-engineered airway with mechanical properties that allow normal functioning, and which is free from the risks of rejection. The findings suggest that autologous cells combined with appropriate biomaterials might provide successful treatment for patients with serious clinical disorders.

In vitro and in vivo proposal of an artificial esophagus

Artificial materials and autologous tissues used for esophageal reconstruction often induce complications like stenosis and leakage at long-term follow-up. This study evaluates the possibility to obtain in vitro an implantable tissue-engineered esophagus composed of homologous esophageal acellular matrix and autologous smooth muscle cells (SMCs). Acellular matrices obtained by detergent-enzymatic method did not present any major histocompatibility complex marker and expressed bFGF as protein, showing angiogenic activity in vivo on the chick embryo chorioallantoic membrane (CAM). Moreover, they supported cell adhesion, and inasmuch as just after 24 h from seeding, the scaffold appeared completely covered by SMCs. To verify the biocompatibility of our constructs, defects created in the porcine esophageal wall were covered using homologous acellular matrices with and without cultures of autologous SMCs. At 3 week from surgery, the patches composed of only acellular matrices showed a more severe inflammatory response and were negative for alpha-smooth muscle actin immunostaining. In contrast, the cell-matrix implants presented ingrowth of SMCs, showing an early organization into small fascicules. Collectively, these results suggest that patches composed of homologous esophageal acellular matrix and autologous SMCs may represent a promising tissue-engineering approach for the repair of esophageal injuries.

Beta amyloid angiogenic activity in vitro and in vivo

Angiogenesis has been suggested as a direct contributor to Alzheimer's disease (AD) pathology. The major pathological hallmarks of AD are the presence of neurofibrillary tangles and, beta-amyloid plaques associated with activated microglia, astrocytes, degenerating neurons and vascular toxicity. In this study, Abeta1-40 and Abeta1-42 peptides, both components of the senile plaques in AD, were used to study their angiogenic activity in vitro, by using normal human cerebral endothelial cells (HCECs), and in vivo, by using the chick embryo chorioallantoic membrane (CAM) assay. Results showed that both peptides stimulate in vitro endothelial cell proliferation, chemotaxis and morphogenesis in Matrigel. Moreover, by using the aorta ring assay, both peptides stimulated the formation of capillary-like structures. An angiogenic response was induced in the CAM assay, similar to that induced by fibroblast growth factor-2 (FGF-2), a well-known angiogenic cytokine. Overall, these data support the hypothesis that Abeta peptides may contribute to angiogenesis occurring in AD and suggest that limiting the pro-angiogenic activity of Abeta peptides may therefore provide a useful target to control angiogenesis associated to AD and therefore limit the disease progression.

Electrospun polyphosphazene nanofibers forin vitro rat endothelial cells proliferation

A large variety of natural and synthetic polymers have been explored as scaffolds for the seeding and growth of different types of cells. To fabricate a scaffold that can be used as a synthetic extracellular matrix (ECM), it is important to replicate the nanoscale dimensions of natural ECM. The electrospinning process allows to produce ultrathin fibers so that this method represents a suitable approach to scaffold fabrication for tissue engineering applications. In this work, the feasibility of obtaining flat or tubular matrices from biocompatible poly[(ethyl phenylalanato)(1.4) (ethyl glycinato)(0.6) phosphazene] by electrospinning was evaluated and the effect of process parameters on the diameter of nanofibers was examined. The adhesion and growth of rat neuromicrovascular endothelial cells cultured on sheets and tubes composed by the polymer with an average fiber diameter of 850 +/- 150 nm were also reported. Microscopic examination of the seeded tubes demonstrated that, after 16 days of incubation, endothelial cells formed a monolayer on the whole surface. These results are the first step to demonstrate that tubes of biodegradable polyphosphazenes might be a feasible model to construct human tissues such as vessels or cardiac valves.