The Masquelet induced membrane technique for reconstructing large diaphyseal defects has been shown to be a promising clinical treatment, yet relatively little is known about the cellular, histological and biochemical make‐up of these membranes and how they produce this positive clinical outcome. We compared cellular make‐up, histological changes and growth factor expression in membranes induced around femur bone defects and in subcutaneous pockets at 2, 4 and 6 weeks after induction, and to the periosteum. We found that membranes formed around bone defects were similar to those formed in subcutaneous pockets; however, both were significantly different from periosteum with regard to structural characteristics, location of blood vessels and overall thickness. Membranes induced at the femur defect (at 2 weeks) and in periosteum contain mesenchymal stem cells (MSCs; STRO‐1⁺) which were not found in membranes induced subcutaneously. BMP‐2, TGFβ and VEGF were significantly elevated in membranes induced around femur defects in comparison to subcutaneously induced membranes, whereas SDF‐1 was not detectable in membranes induced at either site. We found that osteogenic and neovascular activity had mostly subsided by 6 weeks in membranes formed at both sites. It was conclude that cellular composition and growth factor content in induced membranes depends on the location where the membrane is induced and differs from periosteum. Osteogenic and neovascular activity in the membranes is maximal between 2 and 4 weeks and subsides after 6. Based on this, better and quicker bone healing might be achieved if the PMMA cement were replaced with a bone graft earlier in the Masquelet technique. Copyright © 2013 John Wiley & Sons, Ltd.

Introduction: Loss of intestinal integrity has been implicated as an important contributor to the development of excessive inflammation following severe trauma. Thus far, clinical data concerning the occurrence and significance of intestinal damage after trauma remain scarce. This study investigates whether early intestinal epithelial cell damage occurs in trauma patients and, if present, whether such cell injury is related to shock, injury severity and the subsequent inflammatory response. Methods: Prospective observational cohort study in 96 adult trauma patients. Upon arrival at the emergency room (ER) plasma levels of intestinal fatty acid binding protein (i-FABP), a specific marker for damage of differentiated enterocytes, were measured. Factors that potentially influence the development of intestinal cell damage after trauma were determined, including the presence of shock and the extent of abdominal trauma and general injury severity. Furthermore, early plasma levels of i-FABP were related to inflammatory markers interleukin-6 (IL-6), procalcitonin (PCT) and C-reactive protein (CRP). Results: Upon arrival at the ER, plasma i-FABP levels were increased compared with healthy volunteers, especially in the presence of shock (P < 0.01). The elevation of i-FABP was related to the extent of abdominal trauma as well as general injury severity (P < 0.05). Circulatory i-FABP concentrations at ER correlated positively with IL-6 and PCT levels at the first day (r² = 0.19; P < 0.01 and r² = 0.36; P < 0.001 respectively) and CRP concentrations at the second day after trauma (r² = 0.25; P < 0.01). Conclusions: This study reveals early presence of intestinal epithelial cell damage in trauma patients. The extent of intestinal damage is associated with the presence of shock and injury severity. Early intestinal damage precedes and is related to the subsequent developing inflammatory response.

Aim: The size of a bone defect limits the ingrowth of bone-forming cells. Endothelial cell–like differentiated precursor cells (endothelial progenitor cells, EPC) enhance the neovascularization, while marrow stromal cells (MSC) promote the repair of bone defects. Our aim was to evaluate if both types of cells can be cocultivated on a β-tricalcium phosphate (β-TCP) matrix and maintain their differentiation capacity as well as to analyze the biologic activity of these cell constructs in vivo. Methods: MSC from human bone marrow and EPC from buffy coat were used. EPC and MSC, alone or in combination, were seeded on fibronectin-coated β-TCP. After 2, 6, and 10 days the metabolic activity and the endothelial differentiation were tested. On day 10 real-time RT-PCRs for endothelial genes (von Willebrandt factor, vascular endothelial growth factor, and vascular endothelial growth factor-receptor 2), osteogenic genes (osteocalcin, cbfa-1, and collagen-1α), and the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase were performed. Cell-containing constructs were implanted into the critical-size defect of the femur of the nude rat. Bone formation and vascularization was determined after 1 week. Results: MSC and EPC on β-TCP remain metabolically active over 10 days. They maintain their differentiation as measured by means of Dil-ac-LDL uptake (EPC) and gene expression of lineage typical genes (EPC + MSC). Although a potential osteogenic differentiation of MSC was maybe affected negatively, constructs loaded with MSC resulted in an increase of new bone mass. Constructs containing EPC resulted in an improved vasculogenesis in vivo. Discussion: MSC and EPC can be cultivated in combination on a fibronectin-coated β-TCP, thereby partly maintaining their lineage typical gene expression. The results of the in vivo examinations suggest that β-TCP combined with EPC and MSC can used as a suitable tool to foster bone healing.

Large bone defects are commonly treated by replacement with auto- and allografts, which have substantial drawbacks including limited supply, donor site morbidity, and possible tissue rejection. This study aimed to improve bone defect treatment using a custom-made filament for tissue engineering scaffolds. The filament consists of biodegradable polylactide acid (PLA) and a varying amount (up to 20%) of osteoconductive S53P4 bioglass. By employing an innovative, additive manufacturing technique, scaffolds with optimized physico-mechanical and biological properties were produced. The scaffolds feature adjustable macro- and microporosity (200–2000 µm) with adaptable mechanical properties (83–135 MPa). Additionally, controllable calcium release kinetics (0–0.25 nMol/µL after 24 h), tunable mesenchymal stem cell (MSC) adhesion potential (after 24 h by a factor of 14), and proliferation (after 168 h by a factor of 18) were attained. Microgrooves resulting from the 3D-printing process on the surface act as a nucleus for cell aggregation, thus being a potential cell niche for spheroid formation or possible cell guidance. The scaffold design with its adjustable biomechanics and the bioglass with its antimicrobial properties are of particular importance for the preclinical translation of the results. This study comprehensibly demonstrates the potential of a 3D-printed bioglass composite scaffold for the treatment of critical-sized bone defects.