Airway replacement using stented aortic matrices: Long-term follow-up and results of the TRITON-01 study in 35 adult patients.

Over the past 25 years, we have demonstrated the feasibility of airway bioengineering using stented aortic matrices experimentally then in a first-in-human trial (n = 13). The present TRITON-01 study analyzed all the patients who had airway replacement at our center to confirm that this innovative approach can be now used as usual care. For each patient, the following data were prospectively collected: postoperative mortality and morbidity, late airway complications, stent removal and status at last follow-up on November 2, 2021. From October 2009 to October 2021, 35 patients had airway replacement for malignant (n = 29) or benign (n = 6) lesions. The 30-day postoperative mortality and morbidity rates were 2.9% (n = 1/35) and 22.9% (n = 8/35) respectively. At a median follow-up of 29.5 months (range 1-133 months), 27 patients were alive. There have been no deaths directly related to the implanted bioprosthesis. Eighteen patients (52.9%) had stent-related granulomas requiring a bronchoscopic treatment. Ten among 35 patients (28.6%) achieved a stent free survival. The actuarial 2- and 5-year survival rates (Kaplan-Meier estimates) were respectively 88% and 75%. The TRITON-01 study confirmed that airway replacement using stented aortic matrices can be proposed as usual care at our center. Clinicaltrials.gov Identifier: NCT04263129.

Understanding and leveraging cell metabolism to enhance mesenchymal stem cell transplantation survival in tissue engineering and regenerative medicine applications.

In tissue engineering and regenerative medicine, stem cell-specifically, mesenchymal stromal/stem cells (MSCs)-therapies have fallen short of their initial promise and hype. The observed marginal, to no benefit, success in several applications has been attributed primarily to poor cell survival and engraftment at transplantation sites. MSCs have a metabolism that is flexible enough to enable them to fulfill their various cellular functions and remarkably sensitive to different cellular and environmental cues. At the transplantation sites, MSCs experience hostile environments devoid or, at the very least, severely depleted of oxygen and nutrients. The impact of this particular setting on MSC metabolism ultimately affects their survival and function. In order to develop the next generation of cell-delivery materials and methods, scientists must have a better understanding of the metabolic switches MSCs experience upon transplantation. By designing treatment strategies with cell metabolism in mind, scientists may improve survival and the overall therapeutic potential of MSCs. Here, we provide a comprehensive review of plausible metabolic switches in response to implantation and of the various strategies currently used to leverage MSC metabolism to improve stem cell-based therapeutics.

Use of adult mesenchymal stromal cells in tissue repair: impact of physical exercise.

Physical exercise (PE) has unquestionable beneficial effects on health, which likely extend into several organ-to-cell physiological processes. At the cell scale, endogenous mesenchymal stromal cells (MSCs) contribute to tissue repair, although their repair capacities may be insufficient in paucicellular or severely damaged tissues. For this reason, MSC transplantation holds great promise for tissue repair. With the goals of understanding if PE has beneficial effects on MSC biology and if PE potentiates their role in tissue repair, we reviewed literature reports regarding the effects of PE on MSC properties (specifically, proliferation, differentiation, and homing) and of a combination of PE and MSC transplantation on tissue repair (specifically neural, cartilage, and muscular tissues). Contradictory results have been reported; interpretation is complicated because various and different species, cell sources, and experimental protocols, specifically exercise programs, have been used. On the basis of these data, the effects of exercise on MSC proliferation and differentiation depend on exercise characteristics (type, intensity, duration, etc.) and on the characteristics of the tissue from which the MSCs were collected. For the in vitro studies, the level of strain (and other details of the mechanical stimulus), the time elapsed between the end of exposure to strain and MSC collection, the age of the donors, as well as the passage number at which the MSCs are evaluated also play a role. The combination of PE and MSC engraftment improves neural, cartilage, and muscular tissue recovery, but it is not clear whether the effects of MSCs and exercise are additive or synergistic.

Human Mesenchymal Stem Cell Failure to Adapt to Glucose Shortage and Rapidly Use Intracellular Energy Reserves Through Glycolysis Explains Poor Cell Survival After Implantation.

Mesenchymal stem cells (MSCs) hold considerable promise in tissue engineering (TE). However, their poor survival when exogenously administered limits their therapeutic potential. Previous studies from our group demonstrated that lack of glucose (glc) (but not of oxygen) is fatal to human MSCs because it serves as a pro-survival and pro-angiogenic molecule for human MSCs (hMSCs) upon transplantation. However, which energy-providing pathways MSCs use to metabolize glc upon transplantation? Are there alternative energetic nutrients to replace glc? And most importantly, do hMSCs possess significant intracellular glc reserves for ensuring their survival upon transplantation? These remain open questions at the forefront of TE based-therapies. In this study, we established for the first time that the in vivo environment experienced by hMSCs is best reflected by near-anoxia (0.1% O2 ) rather than hypoxia (1%-5% O2 ) in vitro. Under these near-anoxia conditions, hMSCs rely almost exclusively on glc through anerobic glycolysis for ATP production and are unable to use either exogenous glutamine, serine, or pyruvate as energy substrates. Most importantly, hMSCs are unable to adapt their metabolism to the lack of exogenous glc, possess a very limited internal stock of glc and virtually no ATP reserves. This lack of downregulation of energy turnover as a function of exogenous glc level results in a rapid depletion of hMSC energy reserves that explains their poor survival rate. These new insights prompt for the development of glc-releasing scaffolds to overcome this roadblock plaguing the field of TE based-therapies. Stem Cells 2018;36:363-376.

Quiescence Preconditioned Human Multipotent Stromal Cells Adopt a Metabolic Profile Favorable for Enhanced Survival under Ischemia.

A major impediment to the development of therapies with mesenchymal stem cells/multipotent stromal cells (MSC) is the poor survival and engraftment of MSCs at the site of injury. We hypothesized that lowering the energetic demand of MSCs by driving them into a quiescent state would enhance their survival under ischemic conditions. Human MSCs (hMSCs) were induced into quiescence by serum deprivation (SD) for 48 hours. Such preconditioned cells (SD-hMSCs) exhibited reduced nucleotide and protein syntheses compared to unpreconditioned hMSCs. SD-hMSCs sustained their viability and their ATP levels upon exposure to severe, continuous, near-anoxia (0.1% O2 ) and total glucose depletion for up to 14 consecutive days in vitro, as they maintained their hMSC multipotential capabilities upon reperfusion. Most importantly, SD-hMSCs showed enhanced viability in vivo for the first week postimplantation in mice. Quiescence preconditioning modified the energy-metabolic profile of hMSCs: it suppressed energy-sensing mTOR signaling, stimulated autophagy, promoted a shift in bioenergetic metabolism from oxidative phosphorylation to glycolysis and upregulated the expression of gluconeogenic enzymes, such as PEPCK. Since the presence of pyruvate in cell culture media was critical for SD-hMSC survival under ischemic conditions, we speculate that these cells may utilize some steps of gluconeogenesis to overcome metabolic stress. These findings support that SD preconditioning causes a protective metabolic adaptation that might be taken advantage of to improve hMSC survival in ischemic environments. Stem Cells 2017;35:181-196.

Feasibility of Bioengineered Tracheal and Bronchial Reconstruction Using Stented Aortic Matrices.

Importance: Airway transplantation could be an option for patients with proximal lung tumor or with end-stage tracheobronchial disease. New methods for airway transplantation remain highly controversial. Objective: To establish the feasibility of airway bioengineering using a technique based on the implantation of stented aortic matrices. Design, Setting, and Participants: Uncontrolled single-center cohort study including 20 patients with end-stage tracheal lesions or with proximal lung tumors requiring a pneumonectomy. The study was conducted in Paris, France, from October 2009 through February 2017; final follow-up for all patients occurred on November 2, 2017. Exposures: Radical resection of the lesions was performed using standard surgical techniques. After resection, airway reconstruction was performed using a human cryopreserved (-80°C) aortic allograft, which was not matched by the ABO and leukocyte antigen systems. To prevent airway collapse, a custom-made stent was inserted into the allograft. In patients with proximal lung tumors, the lung-sparing intervention of bronchial transplantation was used. Main Outcomes and Measures: The primary outcome was 90-day mortality. The secondary outcome was 90-day morbidity. Results: Twenty patients were included in the study (mean age, 54.9 years; age range, 24-79 years; 13 men [65%]). Thirteen patients underwent tracheal (n = 5), bronchial (n = 7), or carinal (n = 1) transplantation. Airway transplantation was not performed in 7 patients for the following reasons: medical contraindication (n = 1), unavoidable pneumonectomy (n = 1), exploratory thoracotomy only (n = 2), and a lobectomy or bilobectomy was possible (n = 3). Among the 20 patients initially included, the overall 90-day mortality rate was 5% (1 patient underwent a carinal transplantation and died). No mortality at 90 days was observed among patients who underwent tracheal or bronchial reconstruction. Among the 13 patients who underwent airway transplantation, major 90-day morbidity events occurred in 4 (30.8%) and included laryngeal edema, acute lung edema, acute respiratory distress syndrome, and atrial fibrillation. There was no adverse event directly related to the surgical technique. Stent removal was performed at a postoperative mean of 18.2 months. At a median follow-up of 3 years 11 months, 10 of the 13 patients (76.9%) were alive. Of these 10 patients, 8 (80%) breathed normally through newly formed airways after stent removal. Regeneration of epithelium and de novo generation of cartilage were observed within aortic matrices from recipient cells. Conclusions and Relevance: In this uncontrolled study, airway bioengineering using stented aortic matrices demonstrated feasibility for complex tracheal and bronchial reconstruction. Further research is needed to assess efficacy and safety. Trial Registration: clinicaltrials.gov Identifier: NCT01331863.

Contra-lateral hip fracture in the elderly: are decreased body mass index and skin thickness predictive factors?

PURPOSE: A correlation between soft tissue thickness and osteoporosis has been suggested. We aimed to estimate if a low body mass index (BMI) and/or a decrease of skin thickness could estimate the risk of contra-lateral hip fracture. METHODS: First, we performed a retrospective analysis of 1268 patients treated for a hip fracture. The 146 patients who had a contra-lateral hip fractures-study group-were compared with the 1078 patients who did not-control group. Four BMI categories were considered: obese, overweight, normal weight and low weight. Second, we enrolled prospectively 1000 consecutive patients in the emergency department. History of fractures, BMI, and skin aspect on the dorsum of both hands-classified as severe decrease thickness, moderate decrease thickness or normal-were recorded. RESULTS: pt?>In the first part, we found that patients with contra-lateral fractures had a significantly lower BMI than those in the control group (22.2 Vs 26.5 kg/m2, p = 0.01). In the second part, 48 on 1000 patients had a hip fracture. Among them, six had a contra-lateral fracture. BMI was 23.4 kg/m2 in bilateral hip fractures, 33.68 kg/m2 in the unilateral fracture group, and 28.04 kg/m2 in the non-fracture group (p = 0.04). Finally, patients with contra-lateral hip fractures had a severe decrease thickness of the skin. CONCLUSION: A low BMI and a decreased skin thickness increase independently the risk of fractures by three times. When associated, they increase the risk of fracture risk by five times. This combination had a sensitivity at 71 % and a specificity at 90 % for predicting hip fracture.

Proangiogenic and prosurvival functions of glucose in human mesenchymal stem cells upon transplantation.

A major limitation in the development of cellular therapies using human mesenchymal stem cells (hMSCs) is cell survival post-transplantation. In this study, we challenged the current paradigm of hMSC survival, which assigned a pivotal role to oxygen, by testing the hypothesis that exogenous glucose may be key to hMSC survival. We demonstrated that hMSCs could endure sustained near-anoxia conditions only in the presence of glucose. In this in vitro cell model, the protein expressions of Hif-1α and angiogenic factors were upregulated by the presence of glucose. Ectopically implanted tissue constructs supplemented with glucose exhibited four- to fivefold higher viability and were more vascularized compared to those without glucose at day 14. These findings provided the first direct in vitro and in vivo demonstration of the proangiogenic and prosurvival functions of glucose in hMSC upon transplantation and identified glucose as an essential component of the ideal scaffold for transplanting stem cells.

Osseointegration of polyethylene implants coated with titanium and biomimetically or electrochemically deposited hydroxyapatite in a rabbit model.

PURPOSE: The aim of this study was to evaluate the osseointegration of a new coating directly deposited on PE at room temperature. METHODS: Thirty-six (36) male New Zealand rabbits were randomly assigned to receive one out of three types of implants: two tested implants, i.e. PE implant coated with TiPVD and biomimetic HA (biomimetic), PE implant coated with TiPVD and electrolytic HA (electrolytic), and positive control made of massive microrough titanium coated with plasma sprayed HA (TiHAPS). Osseointegration was evaluated by histomorphometry (bone tissue in contact [BIC]), mineralized bone area [MBA]) and mechanical testing (push-out test, interfacial shear strength [ISS]) at six and 12 weeks in the distal femurs. RESULTS: For BIC there were no differences between the groups at six (p = 0.98) and 12 weeks (p = 0.13). For MBA, no statistically significant difference was measured between groups at six (p = 0.52) and 12 weeks (p = 0.57). At six weeks, interfacial shear strength (ISS) was significantly higher (p = 0.01) for TiHAPs implants compared to biomimetic and electrolytic implants. This difference was not significant at 12 weeks (p = 0.92). CONCLUSION: The osseointegration of biomimetic and electrolytic implants was equivalent to a positive control at 12 weeks.

Porosity and surface curvature effects on the permeability and wall shear stress of trabecular bone: Guidelines for biomimetic scaffolds for bone repair.

Scaffolds are an essential component of bone tissue engineering to provide support and create a physiological environment for cells. Biomimetic scaffolds are a promising approach to fulfill the requirements. Bone allografts are widely used scaffolds due to their mechanical and structural characteristics. The scaffold geometry is well known to be an important determinant of induced mechanical stimulation felt by the cells. However, the impact of allograft geometry on permeability and wall shear stress distribution is not well understood. This information is essential for designing biomimetic scaffolds that provide a suitable environment for cells to proliferate and differentiate. The present study investigates the effect of geometry on the permeability and wall shear stress of bone allografts at both macroscopic and microscopic scales. Our results concluded that the wall shear stress was strongly correlated with the porosity of the allograft. The level of wall shear stress at a local scale was also determined by the surface curvature characteristics. The results of this study can serve as a guideline for future biomimetic scaffold designs that provide a mechanical environment favorable for osteogenesis and bone repair.

In Vivo Assessment of Skin Surface Pattern: Exploring Its Potential as an Indicator of Bone Biomechanical Properties.

The mechanical properties of bone tissue are the result of a complex process involving collagen-crystal interactions. The mineral density of the bone tissue is correlated with bone strength, whereas the characteristics of collagen are often associated with the ductility and toughness of the bone. From a clinical perspective, bone mineral density alone does not satisfactorily explain skeletal fragility. However, reliable in vivo markers of collagen quality that can be easily used in clinical practice are not available. Hence, the objective of the present study is to examine the relationship between skin surface morphology and changes in the mechanical properties of the bone. An experimental study was conducted on healthy children (n = 11), children with osteogenesis imperfecta (n = 13), and women over 60 years of age (n = 22). For each patient, the skin characteristic length (SCL) of the forearm skin surface was measured. The SCL quantifies the geometric patterns formed by wrinkles on the skin's surface, both in terms of size and elongation. The greater the SCL, the more deficient was the organic collagen matrix. In addition, the bone volume fraction and mechanical properties of the explanted femoral head were determined for the elderly female group. The mean SCL values of the healthy children group were significantly lower than those of the elderly women and osteogenesis imperfecta groups. For the aged women group, no significant differences were indicated in the elastic mechanical parameters, whereas bone toughness and ductility decreased significantly as the SCL increased. In conclusion, in bone collagen pathology or bone aging, the SCL is significantly impaired. This in vivo skin surface parameter can be a non-invasive tool to improve the estimation of bone matrix quality and to identify subjects at high risk of bone fracture.

A New Microarchitecture-Based Parameter to Predict the Micromechanical Properties of Bone Allografts.

Scaffolds are an essential component of bone tissue engineering. They provide support and create a physiological environment for cells to proliferate and differentiate. Bone allografts extracted from human donors are promising scaffolds due to their mechanical and structural characteristics. Bone microarchitecture is well known to be an important determinant of macroscopic mechanical properties, but its role at the microscopic, i.e., the trabeculae level is still poorly understood. The present study investigated linear correlations between microarchitectural parameters obtained from X-ray computed tomography (micro-CT) images of bone allografts, such as bone volume fraction (BV/TV), degree of anisotropy (DA), or ellipsoid factor (EF), and micromechanical parameters derived from micro-finite element calculations, such as mean axial strain (εz) and strain energy density (We). DAEF, a new parameter based on a linear combination of the two microarchitectural parameters DA and EF, showed a strong linear correlation with the bone mechanical characteristics at the microscopic scale. Our results concluded that the spatial distribution and the plate-and-rod structure of trabecular bone are the main determinants of the mechanical properties of bone at the microscopic level. The DAEF parameter could, therefore, be used as a tool to predict the level of mechanical stimulation at the local scale, a key parameter to better understand and optimize the mechanism of osteogenesis in bone tissue engineering.

Glucose Metabolism: Optimizing Regenerative Functionalities of Mesenchymal Stromal Cells Postimplantation.

Mesenchymal stromal cells (MSCs) are considered promising candidates for regenerative medicine applications. Their clinical performance postimplantation, however, has been disappointing. This lack of therapeutic efficacy is most likely due to suboptimal formulations of MSC-containing material constructs. Tissue engineers, therefore, have developed strategies addressing/incorporating optimized cell, microenvironmental, biochemical, and biophysical cues/stimuli to enhance MSC-containing construct performance. Such approaches have had limited success because they overlooked that maintenance of MSC viability after implantation for a sufficient time is necessary for MSCs to develop their regenerative functionalities fully. Following a brief overview of glucose metabolism and regulation in MSCs, the present literature review includes recent pertinent findings that challenge old paradigms and notions. We hereby report that glucose is the primary energy substrate for MSCs, provides precursors for biomass generation, and regulates MSC functions, including proliferation and immunosuppressive properties. More importantly, glucose metabolism is central in controlling in vitro MSC expansion, in vivo MSC viability, and MSC-mediated angiogenesis postimplantation when addressing MSC-based therapies. Meanwhile, in silico models are highlighted for predicting the glucose needs of MSCs in specific regenerative medicine settings, which will eventually enable tissue engineers to design viable and potent tissue constructs. This new knowledge should be incorporated into developing novel effective MSC-based therapies. Impact statement The clinical use of mesenchymal stromal cells (MSCs) has been unsatisfactory due to the inability of MSCs to survive and be functional after implantation for sufficient periods to mediate directly or indirectly a successful regenerative tissue response. The present review summarizes the endeavors in the past, but, most importantly, reports the latest findings that elucidate underlying mechanisms and identify glucose metabolism as the crucial parameter in MSC survival and the subsequent functions pertinent to new tissue formation of importance in tissue regeneration applications. These latest findings justify further basic research and the impetus for developing new strategies to improve the modalities and efficacy of MSC-based therapies.

Cochlear implant insertion forces in microdissected human cochlea to evaluate a prototype array.

Cochlear implant array insertion forces are potentially related to cochlear trauma. We compared these forces between a standard (Digisonic SP; Neurelec, Vallauris, France) and an array prototype (Neurelec) with a smaller diameter. The arrays were inserted by a mechatronic tool in 23 dissected human cochlea specimens exposing the basilar membrane. The array progression under the basilar membrane was filmed together with dynamic force measurements. Insertion force profiles and depth of insertion were compared. The recordings showed lower insertion forces beyond 270° of insertion and deeper insertions with the thin prototype array. This will potentially allow larger cochlear coverage with less trauma.

Early impairment of cartilage poroelastic properties in an animal model of ACL tear.

BACKGROUND: In more than 50% of cases, anterior cruciate ligament (ACL) lesions lead to post-traumatic osteoarthritis. Ligament reconstruction stabilizes the joint, but the tear seems to impair the poroelasticity of the cartilage: synovial membrane fluid inflammation is observed 3 weeks after tearing. There have been some descriptions of visible cartilage changes, but poroelasticity has never been analyzed at this early stage. The present animal study aimed to determine (1) whether cartilage showed early poroelastic deterioration after ACL tear; (2) whether an impairment correlated with macroscopic changes; and (3) whether cartilage poroelasticity deteriorated over time. HYPOTHESIS: In the days following trauma, cartilage poroelasticity is greatly impaired, without macroscopically visible change. MATERIAL AND METHODS: ACL tear was surgically induced in 18 New-Zealand rabbits. Cartilage poroelasticity was assessed on indentation-relaxation test in 3 groups: "early", at 2 weeks postoperatively (n=6), "mid-early" at 6 weeks (n=6) and in a non-operated control group ("non-op"). Macroscopic changes were scored in the same groups. RESULTS: Poroelastic impairment was greatest at the early time-point (2 weeks). Permeability ranged from a mean 0.08±0.05×10-15 m4/Ns (range, 0.028-0.17) in the "non-op" group to 1.03±0.60×10-15 m4/Ns (range, 0.24-2.15) in the "early" group (p=0.007). Shear modulus ranged from 0.53±0.11MPa (range, 0.36-0.66) to 0.23±0.10MPa (range, 0.12-0.43), respectively (p=0.013). Macroscopic deterioration, on the other hand, differed significantly only between the "mid-early" and the "non-op" groups: p=0.011 for cartilage deterioration and p=0.008 for osteophyte formation. At the "mid-early" time point, poroelastic deterioration was less marked, with 0.33±0.33×10-15 m4/Ns permeability (range, 0.06-1.06) and shear modulus 0.30±0.10MPa (range, 0.13-0.41: respectively p=0.039 and p=0.023 compared to the "non-op" group. DISCUSSION: The severe rapid deterioration in poroelasticity following ACL tear in an animal model, as notably seen in increased permeability, corresponds to changes in cartilage microstructure, with easier outflows of interstitial fluid. This mechanical degradation may underlie onset of microcracks within the cartilage, leading to physiological loading that the cartilage by its nature is unable to repair. Further investigations are needed to correlate these experimental data with clinical findings. LEVEL OF EVIDENCE: III; comparative study with control group.

Remnants-preserving ACL reconstruction using direct tendinous graft fixation: a new rat model.

BACKGROUND: Anterior cruciate ligament (ACL) repair techniques are new emerging strategies prevailing, in selected cases, over standard reconstruction of the ACL with excision of its remnants. Mid-substance ACL tears represent a challenge for ACL repair techniques, and remnants-preserving ACL reconstruction (rp-ACLR) using an autograft remains the recommended treatment in this situation. However, morbidity associated with the autograft harvesting prompts the need for alternative surgical strategies based on the use of synthetic scaffolds. Relevant small animal models of mid-substance tears with ACL remnants preservation and reconstruction are necessary to establish the preliminary proof of concept of these new strategies. METHODS: A rat model of rp-ACLR using a tendinous autograft after complete mid-substance ACL transection was established. Twelve weeks following surgery, clinical outcomes and knee joints were assessed through visual gait analysis, Lachman tests, thigh perimeter measurements, magnetic resonance imaging, micro-computed tomography, and histology, to evaluate the morbidity of the procedure, accuracy of bone tunnel positioning, ACL remnants fate, osteoarthritis, and autograft bony integration. Results were compared with those obtained with isolated ACL transection without reconstruction and to right non-operated knees. RESULTS AND DISCUSSION: Most operated animals were weight-bearing the day following surgery, and no adverse inflammatory reaction has been observed for the whole duration of the study. Autograft fixation with cortical screws provided effective graft anchorage until sacrifice. Healing of the transected ACL was not observed in the animals in which no graft reconstruction was performed. rp-ACLR was associated with a reduced degeneration of the ACL remnants (p = 0.004) and cartilages (p = 0.0437). Joint effusion and synovitis were significantly lower in the reconstructed group compared to the transected ACL group (p = 0.004). Most of the bone tunnel apertures were anatomically positioned in the coronal and/or sagittal plane. The most deviated bone tunnel apertures were the tibial ones, located in median less than 1 mm posteriorly to anatomical ACL footprint center. CONCLUSION: This study presents a cost-effective, new relevant and objective rat model associated with low morbidity for the preliminary study of bio-implantable materials designed for remnants-preserving ACL surgery after mid-substance ACL tear.

FGFR3 overactivation in the brain is responsible for memory impairments in Crouzon syndrome mouse model.

Crouzon syndrome with acanthosis nigricans (CAN, a rare type of craniosynostosis characterized by premature suture fusion and neurological impairments) has been linked to a gain-of-function mutation (p.Ala391Glu) in fibroblast growth factor receptor 3 (FGFR3). To characterize the CAN mutation's impact on the skull and on brain functions, we developed the first mouse model (Fgfr3A385E/+) of this syndrome. Surprisingly, Fgfr3A385E/+ mice did not exhibit craniosynostosis but did show severe memory impairments, a structurally abnormal hippocampus, low activity-dependent synaptic plasticity, and overactivation of MAPK/ERK and Akt signaling pathways in the hippocampus. Systemic or brain-specific pharmacological inhibition of FGFR3 overactivation by BGJ398 injections rescued the memory impairments observed in Fgfr3A385E/+ mice. The present study is the first to have demonstrated cognitive impairments associated with brain FGFR3 overactivation, independently of skull abnormalities. Our results provide a better understanding of FGFR3's functional role and the impact of its gain-of-function mutation on brain functions. The modulation of FGFR3 signaling might be of value for treating the neurological disorders associated with craniosynostosis.

Osteoformation potential of an allogenic partially demineralized bone matrix in critical-size defects in the rat calvarium.

Allogenic demineralized bone matrix has been developed as a reliable alternative to the autologous bone graft. In the present study, we assessed the osteoformation potential of a partially demineralized bone matrix (PDBM) in a paste form obtained without an added carrier. This formulation included the preparation of cancelous bone from femoral heads after decellularision, delipidation, demineralization in HCl and autoclaving at 121 °C. Structural and biochemical characteristics of PDBM were determined using FTIR (Fourier transform infrared spectroscopy), hydroxyproline, DNA content assays, and optical ellipsometry. The osteoformation potential was evaluated in 8-, 6-, and 4-mm-diameter rat-calvarial bone defects by in vivo micro-CT analysis, performed immediately after surgery on days 0, 15, 30, 45, and 60. Moreover, histological and histomorphometric analyses were done on day 60. PDBM was compared to cancelous bone powder (BP) before its partial demineralization. The expression levels of selected inflammation-, angiogenesis-, and bone-related genes were also investigated by RT-PCR, 3, 7, and 14 days after surgery. Compared to the control group, the PDBM group exhibited a significant increase (p < 0.05) in radiopacity in 8-mm- and 6-mm-diameter defects at all time points tested. On day 60, the amount of newly-formed bone was greater (16 and 1.6 folds; p < 0.001; respectively) compared to that in control defects. No bone formation was observed in defects filled with BP regardeless of the size. In 8-mm-diameter defect, PDBM was effective enough to induce the upregulation of genes pertinent to inflammation (i.e., TNFα, IL-6, and IL-8), angiogenesis (i.e., VEGF, VWF), and osteogenesis (ALP, RUNX2, BGLAP, SP7) by day 3 after surgery. This study showed that the tested PDBM deeply influences the early critical events involved in bone regeneration and exhibits efficient osteoformation capacity, making it an attractive graft option for treating defects in periodontal and maxillofacial areas.

Experimental Type 2 Diabetes Differently Impacts on the Select Functions of Bone Marrow-Derived Multipotent Stromal Cells.

Bone marrow-derived multipotent stromal cells (BMMSCs) represent an attractive therapeutic modality for cell therapy in type 2 diabetes mellitus (T2DM)-associated complications. T2DM changes the bone marrow environment; however, its effects on BMMSC properties remain unclear. The present study aimed at investigating select functions and differentiation of BMMSCs harvested from the T2DM microenvironment as potential candidates for regenerative medicine. BMMSCs were obtained from Zucker diabetic fatty (ZDF; an obese-T2DM model) rats and their lean littermates (ZL; controls), and cultured under normoglycemic conditions. The BMMSCs derived from ZDF animals were fewer in number, with limited clonogenicity (by 2-fold), adhesion (by 2.9-fold), proliferation (by 50%), migration capability (by 25%), and increased apoptosis rate (by 2.5-fold) compared to their ZL counterparts. Compared to the cultured ZL-BMMSCs, the ZDF-BMMSCs exhibited (i) enhanced adipogenic differentiation (increased number of lipid droplets by 2-fold; upregulation of the Pparg, AdipoQ, and Fabp genes), possibly due to having been primed to undergo such differentiation in vivo prior to cell isolation, and (ii) different angiogenesis-related gene expression in vitro and decreased proangiogenic potential after transplantation in nude mice. These results provided evidence that the T2DM environment impairs BMMSC expansion and select functions pertinent to their efficacy when used in autologous cell therapies.

Preventive Moderate Continuous Running-Exercise Conditioning Improves the Healing of Non-Critical Size Bone Defects in Male Wistar Rats: A Pilot Study Using µCT.

Although physical exercise has unquestionable benefits on bone health, its effects on bone healing have been poorly investigated. This study evaluated the effects of preemptive moderate continuous running on the healing of non-critical sized bone defects in rats by µCT. We hypothesized that a preemptive running exercise would quicken bone healing. Twenty 5-week-old, male, Wistar rats were randomly allocated to one of the following groups (n = 10): sedentary control (SED) or continuous running (EX, 45 min/d, 5 d/week at moderate speed, for 8 consecutive weeks). A 2 mm diameter bone defect was then performed in the right tibia and femur. No exercise was performed during a 4 week-convalescence. Healing-tissue trabecular microarchitectural parameters were assessed once a week for 4 weeks using µCT and plasma bone turnover markers measured at the end of the study protocol (time point T12). At T12, bone volume fraction (BV/TV; BV: bone volume, TV: tissue volume) of the healing tissue in tibiae and femurs from EX rats was higher compared to that in SED rats (p = 0.001). BV/TV in EX rats was also higher in tibiae than in femurs (p < 0.01). The bone mineral density of the healing tissue in femurs from EX rats was higher compared to that in femurs from SED rats (p < 0.03). N-terminal telopeptide of collagen type I in EX rats was decreased compared to SED rats (p < 0.05), while no differences were observed for alkaline phosphatase and parathyroid hormone. The study provides evidence that preemptive moderate continuous running improves the healing of non-critical sized bone defects in male Wistar rats.