Odontoblastic differentiation of dental pulp stem cells from healthy and carious teeth on an original PCL-based 3D scaffold.

AIMS: To isolate and characterize dental pulp stem cells (DPSCs) obtained from carious and healthy mature teeth extracted when conservative treatment was not possible or for orthodontic reasons; to evaluate the ability of DPSCs to colonize, proliferate and differentiate into functional odontoblast-like cells when cultured onto a polycaprolactone cone made by jet-spraying and prototyped into a design similar to a gutta-percha cone. METHODOLOGY: DPSCs were obtained from nine carious and 12 healthy mature teeth. Then cells were characterized by flow cytometry and submitted to multidifferentiation to confirm their multipotency. These DPSCs were then cultured on a polycaprolactone cone in an odontoblastic differentiation medium. Cell proliferation, colonization of the biomaterial and functional differentiation of cells were histologically assessed. For the characterization, a t-Student test was used to compare the two groups. RESULTS: In all cell cultures, characterization highlighted a mesenchymal stem cell phenotype (CD105+, CD90+, CD73+, CD11b-, CD34-, CD45-, HLA-DR-). No significant differences were found between cultures obtained from carious and healthy mature teeth. DPSCs from both origins were able to differentiate into osteocytes, adipocytes and chondrocytes. Cell colonization was observed both on the surface and in the thickness of polycaprolactone cones as well as a mineralized pericellular matrix deposit composed of type I collagen, alkaline phosphatase, osteocalcin and dentin sialophosphoprotein. CONCLUSIONS: DPSCs were isolated from both carious and healthy mature teeth. They were able to colonize and proliferate within a polycaprolactone cone and could be differentiated into functional odontoblast-like cells.

[Induced membrane technique in oral & maxillofacial reconstruction]. / Technique des membranes induites en chirurgie maxillo-faciale.

Maxillofacial defects reconstruction represents a formidable challenge to achieve both functional and aesthetic goals. To succeed, numerous parameters must be taken into account: patient's general conditions, defect's location, width and type of the defect and eventual donor sites which can provide the tissues. Routine reconstructions include bone transplantation (autologous, homologous or heterologous), implantation of biomaterials and osteogenic distraction. The advantages of these techniques are evident, but they are usually limited by their complexity in patients with bad general health. The technique of induced membranes needs to be more known in maxillofacial surgery.

Decellularization of Wharton's Jelly Increases Its Bioactivity and Antibacterial Properties.

The field of regenerative medicine has recently seen an emerging trend toward decellularized extracellular matrix (ECM) as a biological scaffold for stem cell-delivery. Human umbilical cord represents a valuable opportunity from both technical and ethical point of view to obtain allogenic ECM. Herein, we established a protocol, allowing the full removal of cell membranes and nuclei moieties from Wharton's jelly (WJ) tissue. No alterations in the ECM components (i.e., collagen, GAG content, and growth factors), physical (i.e., porosity and swelling) and mechanical (i.e., linear tensile modulus) properties were noticed following WJ processing. Furthermore, no effect of the tissue processing on macromolecules and growth factors retention was observed, assuring thus a suitable bioactive matrix for cell maintenance upon recellularization. Based on the in vitro and in vivo biodegradability and stromal cell homing capabilities, decellularized WJ could provide an ideal substrate for stromal cells adhesion and colonization. Interestingly, the tissue processing increased the antibacterial and antiadhesive properties of WJ against Staphylococcus aureus and Staphylococcus epidermidis pathogens. Altogether, our results indicate that decellularized WJ matrix is able to limit Staphylococcus-related infections and to promote stromal cell homing, thus offering a versatile scaffold for tissue regenerative medicine.

Cartilage graft from rib to treat trapeziometacarpal arthritis.

Trapeziectomy has been considered as the gold standard for treating trapeziometacarpal arthritis. But trapezial space collapse is responsible for thumb strength decrease and intracarpal deformities (with or without tendon interposition). Partial trapeziectomy with interposition of a chondrocostal autograft combines the advantages of trapeziectomy and a biological spacer without the disadvantages of arthroplasty. Partial trapeziectomy is performed by a dorsal approach, under regional anaesthesia. The graft is harvested by a direct approach of the 9th rib during a short bout of general anaesthesia and inserted in the trapeziectomy space. A thumb spica cast is used for 3-6 weeks. In our experience, long-term outcomes and radiological evolution of the graft are good, similar to that of other procedures reported in the literature, except for strength, which is better in this scenario. With more than 5 years of follow-up, the graft is viable, the length of the thumb is maintained, and any areas of graft metaplasia are localized. The result is stable over time and any donor site morbidity is anecdotal. The interposition of a biological material is feasible and produces a stable and strong thumb.

Management of forearm bone loss with induced membrane technique.

There are very few published studies describing the treatment of segmental bone defects of the forearm using the induced membrane technique. The objectives of this study were to evaluate the time to bone union, the function of the joints above and below the treated bone segment and the patients' quality of life over the long-term. We performed a retrospective study in all patients treated by the induced membrane for a forearm bone defect over at 13-year period. Demographics, bone union, complications, functional outcomes and occupational status were collected. Six patients were included: 2 posttraumatic injuries, 1 osteomyelitis, 1 septic arthritis, 1 aseptic nonunion, 1 tumor. The average defect length was 64mm (48-110). All defects were treated with internal fixation. Bone graft was harvested from the iliac crest in two patients, the femur (using the Reamer Irrigator Aspirator technique) in three patients and the radius in one patient. Five patients achieved bone union after a mean of 4months (3-6). Three complications were observed: 1 radioulnar instability, 1 infection of the fixation device, 1 abscess. At an average 8½ years' follow-up, the pain level on the VAS was 0.6 (0-3), the Mayo Elbow Performance Score was 98 (90-100), the Herzberg score was 108 (85.6-140) and the QuickDASH was 14.9 (2.7-35). All patients returned to work. Using the induced membrane technique avoids the complications associated with vascularized autograft and yields good functional outcome and quality of life.

Can the amniotic membrane be used to treat peripheral nerve defects? A review of literature.

Human amniotic membrane is currently being used in ophthalmology and dermatology applications. The objective of this review was to establish proof-of-concept for using amniotic membrane to treat peripheral nerve defects. We performed a search using: 1) PubMed with the keywords/MeSH terms: "amnion", "amniotic membrane", "angiogenesis", "anti-microbial", "characteristic", "chorion", "epithelialization", "fibrosis", "gap", "growth factors", "use", "nerve"; 2) the American clinical trials registry with "amniotic membrane"; 3) Lim Jeremy's book "A primer on amniotic membrane regenerative healing"; 4) the search engine Google. Our findings pointed to the amniotic membrane being a biodegradable and bioactive scaffold that contains many growth factors important for efficient nerve regeneration. Multiple animal studies and the single human clinical trial performed up to now have highlighted its role in preventing recurrence of perineural adhesions, reducing fibrosis, accelerating nerve repair and improving nerve function. Thus, the amniotic membrane has ideal properties for treating peripheral nerve injuries. It could very likely prevent neuroma formation. The best format would be a freeze-dried one containing the amnion and chorion layers in order to preserve all its growth factors, and facilitate its handling and storage in the operating room.

Functional and radiographic evaluation of the treatment of traumatic bone loss of the hand using the Masquelet technique.

This study was a retrospective evaluation of 18 patients with traumatic bone loss affecting the fingers, hand and wrist who were treated using the induced-membrane technique. Sixteen men and two women, mean age 54years (27-74) presented a hand injury including bone loss. Sixteen patients were treated on an emergency basis and two following nonunion of their fractures. There were 13 cases of open fracture of the phalanx and 5 cases of metacarpal fractures. These patients were treated with debridement and the injuries were covered when necessary. To address the bone loss, the first step of the induced-membrane technique involved placing a cement spacer (polymethylmethacrylate [PMMA]) without antibiotics in the defect. During the second step, the cement spacer was removed and replaced by autologous cancellous bone graft. The graft was placed within the biological tube left empty after removal of the cement. For each patient, bone union was assessed with radiographs and/or CT scan. Failure was defined as nonunion at 1year. In 16 patients, the fractures had healed after 4months (1.5-12months) on average. Two failures were noted (one nonunion treated using a PIP prosthesis and one case of delayed union). Mobility of the fingers, evaluated using the Total Active Motion (TAM) was 145° (75°-270°). The Kapandji score reached 8 for the thumb. Grip strength reached 21kg/F and pinch strength was 5kg/F; these values were 50% of those in the healthy hand. The induced-membrane technique is simple and can be used to treat traumatic bone loss in an emergency, thus avoiding amputation and limb shortening, while preserving limb function. It provides immediate stability and allows early mobilization.

Osteotomy and fracture fixation in children and teenagers.

Significant changes have occurred recently in fixation methods following fracture or osteotomy in children and teenagers. Children have benefited the most from these advances. A child's growth is anatomically and physiologically ensured by the growth plate and periosteum. The need to keep the periosteum intact during trauma cases has led to the introduction of flexible intramedullary nailing. We will review the basic principles of this safe, universally adopted technique, and also describe available material, length and diameter options. The problems and the limitations of this method will be discussed extensively. In orthopedics, the desire to preserve the periosteum has led to the use of locking compression plates. Because of their low profile and high stability, they allow the micromovements essential for bone union. These new methods reduce the immobilization period and allow autonomy to be regained more quickly, which is especially important in children with neurological impairment. The need to preserve the growth plate, which is well known in pediatric surgery, is reviewed with the goal of summarizing current experimental data on standard fracture and osteotomy fixation methods. Adjustable block stop wires provide better control over compression. These provide an alternate means of fixation between K-wires and screws (now cannulated) and have contributed to the development of minimally invasive surgical techniques. The aim of this lecture is to provide a rationale for the distinct technical features of pediatric surgery, while emphasizing the close relationship between the physiology of growth, bone healing and technical advances.

[Induced membrane technique for the reconstruction of bone defects in upper limb. A prospective single center study of nine cases]. / Reconstruction des pertes de substance osseuse du membre supérieur par la technique de la membrane induite, étude prospective à propos de neuf cas.

INTRODUCTION: Bone defect in the upper limb remain infrequent with few reported in the literature. Their reconstruction raises the problem of bone union of non weight-bearing segments as well as the function of adjacent joints. We report a monocentric continuous series of nine patients treated with the induced membrane technique (Masquelet technique). PATIENTS AND METHODS: Nine patients with a mean age of 39.2 years (17-69) presented with a bone defect of the humerus (six cases) or one of two bones (three cases). Diaphyseal (six cases) or metaphyseal (three cases) defects were secondary to trauma in three patients, to non-union in four others and following tumors for the other two. The mean defect was 5.1cm (2.5-9). Reconstruction was done by initial filling using a spacer in cement, followed by a cancellous bone graft within the induced membrane. BMP's growth factor was used in two cases. RESULTS: Bone union was achieved in eight out of nine cases with a follow-up of 23 months (8-52) after the first stage, and 17 months (6-49) following filling by the graft. One patient did not want the second stage done before one year. The failure was in a very non-compliant patient who had a bone substitute associated with aBMP. Two septic non-unions were cured. Shoulder and elbow functional outcomes were comparable to the controlateral side for humeral defects; pronosupination decreased by 17% for the cases of reconstruction of two bones. DISCUSSION: The technique of the induced membrane allows filling of a large bone defect, while avoiding vascularised bone autografts and their morbidity. It requires two procedures but can be used in emergency or after failure of other interventions. It is a reliable, and reproducible technique where the only limit is the cancellous bone stock. Following the series of Masquelet, Apard and Stafford in the lower limb, and the series of Flamans in the hand, this is the first report of reconstruction of defect in the upper limb using this technique.

Bone morphogenetic proteins in soft-tissue reconstruction.

Different options are reviewed in the field of musculoskeletal tissue reconstruction, from the addition of biological actors (cells, growth factors, biological or artificial scaffolds) to the application of gene therapy or tissue engineering. Growth factors can enable innovative solutions to treat such disease if we can extrapolate to soft tissue the promising results obtained in bone reconstruction with bone morphogenetic proteins. However, as in bone reconstruction, soft-tissue regeneration will depend on the drug delivery carrier, the scaffold for the newly formed tissue, the dose of growth factor and the animal model, which must all be explored before extrapolation to clinical problems.

Human and rodent bone marrow mesenchymal stem cells that express primitive stem cell markers can be directly enriched by using the CD49a molecule.

Bone marrow (BM) from human and rodent species contains a population of multipotential cells referred to as mesenchymal stem cells (MSCs). Currently, MSCs are isolated indirectly by using a culture step and then the generation of fibroblast colony-forming units (CFU-fs). Unprocessed or native BM MSCs have not yet been fully characterised. We have previously developed a direct enrichment method for the isolation of MSCs from human BM by using the CD49a protein (alpha1-integrin subunit). As the CD49a gene is highly conserved in mammals, we have evaluated whether this direct enrichment can be employed for BM cells from rodent strains (rat and mouse). We have also studied the native phenotype by using both immunodetection and immunomagnetic methods and have compared MSCs from mouse, rat and human BM. As is the case for human BM, we have demonstrated that all rodent multipotential CFU-fs are contained within the CD49a-positive cell population. However, in the mouse, the number of CFU-fs is strain-dependent. Interestingly, all rat and mouse Sca-1-positive cells are concentrated within the CD49a-positive fraction and also contain all CFU-fs. In human, the colonies have been detected in the CD49a/CD133 double-positive population. Thus, the CD49a protein is a conserved marker that permits the direct enrichment of BM MSCs from various mammalian species; these cells have been phenotyped as true BM stem cells.