Flore Lesage

Few Smad proteins and many Smad-interacting proteins yield multiple functions and action modes in TGFβ/BMP signaling in vivo

Signaling by the many ligands of the TGFβ family strongly converges towards only five receptor-activated, intracellular Smad proteins, which fall into two classes i.e. Smad2/3 and Smad1/5/8, respectively. These Smads bind to a surprisingly high number of Smad-interacting proteins (SIPs), many of which are transcription factors (TFs) that co-operate in Smad-controlled target gene transcription in a cell type and context specific manner. A combination of functional analyses in vivo as well as in cell cultures and biochemical studies has revealed the enormous versatility of the Smad proteins. Smads and their SIPs regulate diverse molecular and cellular processes and are also directly relevant to development and disease. In this survey, we selected appropriate examples on the BMP-Smads, with emphasis on Smad1 and Smad5, and on a number of SIPs, i.e. the CPSF subunit Smicl, Ttrap (Tdp2) and Sip1 (Zeb2, Zfhx1b) from our own research carried out in three different vertebrate models.

Evaluating Alternative Materials for the Treatment of Stress Urinary Incontinence and Pelvic Organ Prolapse: A Comparison of the In Vivo Response to Meshes Implanted in Rabbits.

PURPOSE Serious complications can develop with the mesh implants used for stress urinary incontinence and pelvic organ prolapse surgery. We evaluated 2 materials currently in clinical use and 2 alternative materials using a rabbit abdominal model to assess host response and biomechanical properties of the materials before and after implantation. MATERIALS AND METHODS Poly-L-lactic acid and polyurethane meshes were electrospun to be compared to commercially available polypropylene and polyvinylidene fluoride meshes. A total of 40 immunocompetent full-thickness abdominal wall defect rabbit models were used, including 8 in each of the poly-L-lactic acid, polyurethane, polyvinylidene fluoride and polypropylene experimental groups, and sham controls. Two 20 mm defects were created per animal and primarily repaired. The experimental groups then underwent onlay of each repair material while sham controls did not. Four rabbits per group were sacrificed at days 30 and 90. Abdominal wall specimens containing the defect with or without repair material were explanted to be assessed by histology (hematoxylin and eosin staining, and immunohistochemistry) and biomechanical testing at 30 and 90 days. RESULTS At 90 days of implantation tissues repaired with all 4 materials showed biomechanical properties without significant differences. However, polypropylene and polyvinylidene fluoride meshes demonstrated a sustained chronic inflammatory response profile by 90 days. In contrast, poly-L-lactic acid and polyurethane meshes integrated well into host tissues with a decreased inflammatory response, indicative of constructive remodeling. CONCLUSIONS Poly-L-lactic acid and polyurethane alternative materials achieved better host integration in rabbit models than current synthetic repair materials.

Safe and effective cryopreservation methods for long-term storage of human-amniotic-fluid-derived stem cells

Stem cells (SCs) can be isolated from amniotic fluid (AF) for a variety of perinatal applications. In view of this, we compared different cryopreservation protocols for these AFSCs.

Medical and Regenerative Solutions for Congenital Diaphragmatic Hernia: A Perinatal Perspective

In the EU-27, 2,100 babies with congenital diaphragmatic hernia (CDH) are born annually. CDH is fatal in 30% of them. Experimental fetal surgery in severe cases results in a survival rate of 50 to 60% at its best. Failure is due to insufficient lung growth, persistent pulmonary hypertension or prematurity induced by the procedure. For nonsurvivors alternative strategies are required. Survivors undergo anatomical repair, but large diaphragmatic defects are closed using a patch. At present the used materials are less than ideal, mainly because of recurrence and chest deformation. To overcome the above limitations, alternative medical therapies (pharmacologic or cell therapy) that are more potent and less invasive are needed. Also a more functional postnatal repair may be possible when using novel scaffolds or engineered constructs. We see a prominent place for autologous amniotic fluid-derived stem cells for these novel strategies, which could be prenatally harvested following appropriate patient selection by noninvasive imaging.

Preclinical evaluation of cell-based strategies to prevent or treat bronchopulmonary dysplasia in animal models: a systematic review

Abstract Bronchopulmonary dysplasia (BPD) remains the most common complication of extreme prematurity as no effective treatment is available to date. This calls for the exploration of new therapeutic options like cell therapy, which is already effective for various human (lung) disorders. We systematically searched the MEDLINE, Embase, and Web of Science databases from the earliest date till January 2017 and included original studies on the perinatal use of cell-based therapies (i.e. cells and/or cell-derivatives) to treat BDP in animal models. Fourth publications describing 47 interventions were retrieved. Newborn mice/rats raised in a hyperoxic environment were studied in most interventions. Different cell types – either intact cells or their conditioned medium – were administered, but bone marrow and umbilical cord blood derived mesenchymal stem cells were most prevalent. All studies reported positive effects on outcome parameters including alveolar and vascular morphometry, lung function, and inflammation. Cell homing to the lungs was demonstrated in some studies, but the therapeutic effects seemed to be mostly mediated via paracrine modulation of inflammation, fibrosis and angiogenesis. Conclusion: Multiple rat/mouse studies show promise for cell therapy for BPD. Yet careful study of action mechanisms and side effects in large animal models is imperative before clinical translation can be achieved.

Upregulation of Vascular Endothelial Growth Factor in Amniotic Fluid Stem Cells Enhances Their Potential to Attenuate Lung Injury in a Preterm Rabbit Model of Bronchopulmonary Dysplasia

Background: Bronchopulmonary dysplasia (BPD) is a chronic lung disease that affects extremely preterm infants and remains – despite improvements in neonatal intensive care – a major cause of neonatal mortality and morbidity. Cell-therapeutic strategies employing mesenchymal stem cells (MSC) have been shown to modulate lung development in BPD models. Objective: Herein, we evaluate the potential of human amniotic fluid (hAF)-SC and hAF-SC with upregulated expression of vascular endothelial growth factor (VEGF) as cell-therapeutic agents for BPD. Methods: Preterm rabbit pups were raised in normoxia (21% O2) or hyperoxia (≥95% O2). Hyperoxia-exposed pups randomly received an intraperitoneal injection of fibroblasts, naïve hAF-SC, or hAF-SC-VEGF on postnatal day (PN) 0. On PN7, surviving pups were tested for pulmonary (forced oscillation technique) and vascular (pulmonary artery Doppler ultrasound) function, and lungs were processed for morphometric measurements of parenchymal and vascular structure and inflammation. Results: Intraperitoneal injection of cells resulted in homing to the lungs. The lungs of hyperoxia-exposed animals displayed parenchymal and vascular structural and functional damage reminiscent of BPD, which was significantly improved after treatment with hAF-SC-VEGF. Treating hyperoxia-exposed animals with naïve AF-SC attenuated only the lung inflammation and the vascular structural defect. Treatment with fibroblasts, which were used as a cellular control, did not lead to any improvements. Conclusion: hAF-SC with upregulated VEGF expression display enhanced potential to prevent/reverse lung injury in preterm rabbits, whereas naïve hAF-SC only show a moderate therapeutic potential. These results point towards an added value of VEGF delivered by hAF-SC in the treatment of BPD.

The amniotic fluid as a source of mesenchymal stem cells with lung‐specific characteristics

The amniotic fluid is a clinically accessible source of mesenchymal stem cells (AF‐MSC) during gestation, which enables autologous cellular therapy for perinatal disorders. The origin of AF‐MSC remains elusive: renal and neuronal progenitors have been isolated from the AF‐MSC pool, yet no cells with pulmonary characteristics.

Modulation of the Early Host Response to Electrospun Polylactic Acid Matrices by Mesenchymal Stem Cells from the Amniotic Fluid

Purpose The reconstruction of congenital diaphragmatic hernia or other congenital soft tissue defects often requires implants. These can be either degradable or permanent, each having their advantages. Whatever type is being used, the host response induced by implants plays a crucial role to determine the outcome. Macrophages are pivotal during implant remodeling; they are plastic and acquire in response to environmental stimuli either an inflammatory status and mediate subsequent fibrosis or a regulatory status and facilitate functional remodeling. Matrices engineered with mesenchymal stem cells (MSCs) have the capacity to modulate the host immune reaction. MSCs are believed to promote constructive remodeling of the implant through a regulatory macrophage response among others. Herein, we evaluate this potential of MSC derived from the amniotic fluid (AF‐MSC), an interesting MSC type for neonatal reconstruction, on electrospun polylactic acid (PLA) scaffolds. Methods We seeded AF‐MSC at a density of 1.105/cm2 on electrospun PLA matrices and determined cell viability. In vivo, we used cell‐seeded or cell‐free PLA matrices for subcutaneous implantation in immune competent rats. The host immune response was evaluated by histomorphometry at 14 days postoperatively. Results The PLA matrix supported adherence and proliferation of AF‐MSC. Fourteen days after implantation, PLA matrices were well penetrated by inflammatory cells, new blood vessels, and collagen fibers. AF‐MSC‐seeded scaffolds were associated with a similar response yet with a decreased number of eosinophils, increased matrix degradation and collagen fiber deposition compared with controls. The amount of total macrophages and of M2‐subtype was similar for all animals. Conclusion Electrospun PLA matrices are a suitable substrate for short‐term culture of AF‐MSC. In rats, addition of AF‐MSC to PLA matrices modulates the host response after subcutaneous implantation, yet without a difference in macrophage profile compared with control.