Decellularized vascularized bone grafts: A preliminary in vitro porcine model for bioengineered transplantable bone shafts

Introduction: Durable reconstruction of critical size bone defects is still a surgical challenge despite the availability of numerous autologous and substitute bone options. In this paper, we have investigated the possibility of creating a living bone allograft, using the perfusion/decellularization/recellularization (PDR) technique, which was applied to an original model of vascularized porcine bone graft.Materials and Methods: 11 porcine bone forelimbs, including radius and ulna, were harvested along with their vasculature including the interosseous artery and then decellularized using a sequential detergent perfusion protocol. Cellular clearance, vasculature, extracellular matrix (ECM), and preservation of biomechanical properties were evaluated. The cytocompatibility and in vitro osteoinductive potential of acellular extracellular matrix were studied by static seeding of NIH-3T3 cells and porcine adipose mesenchymal stem cells (pAMSC), respectively.Results: The vascularized bone grafts were successfully decellularized, with an excellent preservation of the 3D morphology and ECM microarchitecture. Measurements of DNA and ECM components revealed complete cellular clearance and preservation of ECM’s major proteins. Bone mineral density (BMD) acquisitions revealed a slight, yet non-significant, decrease after decellularization, while biomechanical testing was unmodified. Cone beam computed tomography (CBCT) acquisitions after vascular injection of barium sulphate confirmed the preservation of the vascular network throughout the whole graft. The non-toxicity of the scaffold was proven by the very low amount of residual sodium dodecyl sulfate (SDS) in the ECM and confirmed by the high live/dead ratio of fibroblasts seeded on periosteum and bone ECM-grafts after 3, 7, and 16 days of culture. Moreover, cell proliferation tests showed a significant multiplication of seeded cell populations at the same endpoints. Lastly, the differentiation study using pAMSC confirmed the ECM graft’s potential to promote osteogenic differentiation. An osteoid-like deposition occurred when pAMSC were cultured on bone ECM in both proliferative and osteogenic differentiation media.Conclusion: Fully decellularized bone grafts can be obtained by perfusion decellularization, thereby preserving ECM architecture and their vascular network, while promoting cell growth and differentiation. These vascularized decellularized bone shaft allografts thus present a true potential for future in vivo reimplantation. Therefore, they may offer new perspectives for repairing large bone defects and for bone tissue engineering

3D histopathology of stenotic aortic valve cusps using ex vivo microfocus computed tomography

BackgroundCalcific aortic stenosis (AS) is the most prevalent heart valve disease in developed countries. The aortic valve cusps progressively thicken and the valve does not open fully due to the presence of calcifications. In vivo imaging, usually used for diagnosis, does not allow the visualization of the microstructural changes associated with AS.MethodsEx vivo high-resolution microfocus computed tomography (microCT) was used to quantitatively describe the microstructure of calcified aortic valve cusps in full 3D. As case study in our work, this quantitative analysis was applied to normal-flow low-gradient severe AS (NF-LG-SAS), for which the medical prognostic is still highly debated in the current literature, and high-gradient severe AS (HG-SAS).ResultsThe volume proportion of calcification, the size and number of calcified particles and their density composition was quantified. A new size-based classification considering small-sized particles that are not detected with in vivo imaging was defined for macro-, meso- and microscale calcifications. Volume and thickness of aortic valve cusps, including the complete thickness distribution, were also determined. Moreover, changes in the cusp soft tissues were also visualized with microCT and confirmed by scanning electron microscopy images of the same sample. NF-LG-SAS cusps contained lower relative amount of calcifications than HG-SAS. Moreover, the number and size of calcified objects and the volume and thickness of the cusps were also lower in NF-LG-SAS cusps than in HG-SAS.ConclusionsThe application of high-resolution ex vivo microCT to stenotic aortic valve cusps provided a quantitative description of the general structure of the cusps and of the calcifications present in the cusp soft tissues. This detailed description could help in the future to better understand the mechanisms of AS

Le visage, le masque et le temps. Histoire naturelle de l'architecture segmentaire de la face.

Extending from the supra-occipital region down to both clavicles, the face is an original anatomical entity which constituTes the main field of interaction between the brain and the external world. We here demonstrate that essential structures arise from the neural crest cells and that the segmental migratory pathway of these cells leads to the segmental ontogenesis of the head, and of the anterior neck area from seven distinct morphogenetic units which enjoy each of an independEnt growth potential. In the adult, the neural and segmental origin of the face is temporarily masked by the superficial musculoaponevrotic system which supports its cutaneous cover. Nevertheless, this fundamental architecture appears fugitively in the mimics of facial expression, then more obviously in the ptotic and folding phenomenons involved in cephalic skin ageing

[Imaginary chronicle of Louis XIV's ailments and contemporary illnesses]

Based on contemporary medical journals, the author examines the numerous ailments that afflicted Louis XIV and underlines the impoverishment of the medical art at a time when physicians power was sovereign and when treatments were as bizarre as they were painful. This historical journey also serves as a pretext to examine current developments in the field of microsurgery, which can cure health disorders that were considered inaccessible to anatomical and functional amelioration

Chronique imaginaire de la santé du Roi Louis XIV et des malades de son siècle.

Based on contemporary medical journals, the author examines the numerous ailments that afflicted Louis XIV and underlines the impoverishment of the medical art at a time when physicians' power was sovereign and when treatments were as bizarre as they were painful. This historical journey also serves as a pretext to examine current developments in the field of microsurgery, which can cure health disorders that were considered inaccessible to anatomical and functional amelioration