Engineered bone tissue to recreate the continuity of damaged skeletal segments is one of the field of interest of tissue engineering. Trabecular titanium has very good mechanical properties and high in vitro and in vivo biocompatibility: it can be used in biomedical applications to promote osteointegration demonstrating that it can be successfully used for regenerative medicine in orthopaedic surgery (1). Purpose of this investigation was to evaluate the behavior of adipose tissue derived stem cells (hASCs) cultured on scaffolds of Trabecular TitaniumTM (Lima-Lto) (TT). hASCs are considered to be multipotent mesenchymal stem cells that are easily induced to differentiate into functional osteoblasts both in vitro and in vivo (2). The hASCs were obtained from the subcutaneous adipose tissue of healthy donors during total hip replacement procedures after digestion with collagenase. They were seeded on monolayer and on the TT scaffolds, and incubated at 37 degrees C in 5% CO2 with osteogenic medium or control medium. The expression of bone-related genes using RT-PCR, time course of alkaline phosphatase activity and morphological investigation with Scanning Electron Microscopy (SEM) were performed to evaluate the osteogenic differentiation of hASCs. Alkaline phosphatase activity, marker of the differentiation toward the osteogenic pattern, was significantly higher in hASCs grown with osteogenic medium than in cells grown with control medium, both in monolayer and TT scaffolds; moreover, also alkaline phosphatase of hASCs grown on TT scaffolds in the presence of control medium increased with time, differently from that of cells grown on monolayer. The osteogenic differentiated hASCs expressed the bone-related genes type I collagen, osteocalcin, Runx-2 and alkaline phosphatase. SEM observations showed that hASCs differentiated toward osteoblast-like cells: they produced a big amount of extracellular matrix that covered the surface of the porous scaffolds with bridges between the pore walls. These data suggest that hASCs are able to adhere to TT scaffolds, to acquire an osteoblastic phenotype and to produce abundant extracellular matrix, with but also without osteogenic medium. We can therefore conclude that this material carries osteinductive properties being responsible of ostegenic differentiation; consequently, this scaffold/cells construct is effective to regenerate damaged tissue and to restore the function of bone tissue

Introduction. Regenerative medicine is a rapidly expanding discipline. However due to a lack of validated outcome measures, clinical trials have been far few. This study aims to assess the validity, inter-observer reliability and intra-observer reproducibility of experimental fracture healing assessment on plain radiographies. This technique involves implantation of mesenchymal stem cell (MSC) seeded constructs on only one side of the fracture after randomisation. Methods. We examined inter/intraobserver agreement on the area and “bridging length” of callus formed on opposite sides of the fracture. Among 16 orthopaedic surgeons with trauma commitments (8 consultants, 8 registrars) on two separate occasions (average 52 days apart). They independently assessed the radiographs (AP or lateral) of 28 patients with fractures of the tibial or femoral shaft. The fractures chosen included non-unions treated with MSC/constructs and fresh fractures at 4–9 months. For each radiograph the assessor assigned which side (medial or lateral) is there more callus. Chase-corrected agreement using Fleiss kappa was used to compare opinions. Digital analysis software (Image-J) was used to quantify extent/bridging callus and correlate it with surgeons opinion. Results. Inter-observer variation showed a substantial overall agreement (k = 0.716) on the fracture side containing a larger “area” of callus but moderate agreement (k = 0.489) on side with more “bridging length”. These results were reproducible with a substantial overall intraobserver agreement. MSC/construct treated non-union showed a larger amount of agreement than fresh fractures for area (k = 0.754 vs 0.613) and bridging (0.550 vs 0.406). Utilizing digital analysis, non-unions showed a significant larger quantifiable difference between sides than fresh fractures (p = 0.009) for area but not bridging length (p = 0.269). Digital analysis quantification and surgeons opinion showed an almost perfect agreement for area (k = 0.867) and bridging (k = 0.846). Discussion. In this study we aimed to validate a novel method at studying the efficacy and effect of regenerative techniques on fracture healing. In particular, plain radiographs for comparing a treatment/internal control side. In this study we showed this method assessing area of callus is valid, reliable and reproducible. This is particularly so for MSC/construct treated non-union where the difference in both sides is higher as quantified in digital analysis. This is a novel method of experimental fracture healing using an internal control which decreases the variation between groups and sample size needed. This makes regenerative medicine clinical trials easier

The scarcity of mesenchymal stem cells (MSCs) in iliac crest bone marrow aspirate (ICBMA), and the expense and time in culturing cells, has led to the search for alternative harvest sites. The reamer-irrigation-aspirator (RIA) provides continuous irrigation and suction during reaming of long bones. The aspirated contents pass via a filter, trapping bony fragments, before moving into a ‘waste’ bag from which MSCs have been previously isolated. We examined the liquid and solid phases, performed a novel digestion of the solid phase, and made a comparative assessment in terms of number, phenotype and differentiation capacity with matched ICBMA.

The solid fraction from the filtrate was digested for 60 minutes at 37°C with collagenase. Enumeration was performed via the colony-forming unit fibroblast (CFU-F) assay. Passage (P2) cells were differentiated towards osteogenic, adipogenic and chondrogenic lineages, and their phenotypes assessed using flow cytometry (CD33, CD34, CD45, CD73, CD90, and CD105).

MSCs from the RIA phases were able to differentiate at least as well as those from ICBMA, and all fractions had phenotypes consistent with other established sources. The median number of colonies for the three groups was: ICBMA = 8.5 (2 to 86), RIA-liquid = 19.5 (4 to 90), RIA-solid = 109 (67 to 200) per 200 μl. The mean total yield of cells for the three groups was: ICBMA = 920 (0 to 4275), RIA-liquid = 114 983 (16 500 to 477 750), RIA-solid = 12 785 (7210 to 28 475).

The RIA filtrate contains large numbers of MSCs that could potentially be extracted without enzymatic digestion and used for bone repair without prior cell expansion.