Biomedical subjects

Christophe Trojani

Publications and source records attributed to Christophe Trojani.

4 recordsLinked to original sources

PubMed2006

Ectopic bone formation using an injectable biphasic calcium phosphate/Si-HPMC hydrogel composite loaded with undifferentiated bone marrow stromal cells.

We have used a new synthetic injectable composite constituted of hydroxyapatite/tricalcium phosphate (HA/TCP) particles in suspension in a self-hardening Si-hydroxypropylmethylcellulose (HPMC) hydrogel. The aim of this study was to evaluate in vivo the biocompatibility and the new bone formation efficacy of this scaffold loaded with undifferentiated bone marrow stromal cells (BMSCs). This biomaterial was mixed extemporaneously with BMSCs prepared from C57BL/6 mice, injected in subcutaneous and intramuscular sites and retrieved 4 and 8 weeks after implantation. Dissection of the implants revealed a hard consistency and the absence of a fibrous capsule reflecting a good integration into the host tissues. Histological analysis showed mineralized woven bone in the granule inter-space with numerous active osteoclasts attached to the particles as assessed by the presence of multinucleated cells positively stained for TRAP activity and for the a3 subunit of the V-ATPase. Small vessels were homogenously distributed in the whole implants. Similar results were obtained in SC and IM sites and no bone formation was observed in the control groups when cell-free and particle-free transplants were injected. These results indicate that this injectable biphasic calcium phosphate-hydrogel composite mixed with undifferentiated BMSCs is a new promising osteoinductive bone substitute. It also provides with an original in vivo model of osteoclast differentiation and function.

Animals↗

PubMed2006

Proximal humerus fracture sequelae: impact of a new radiographic classification on arthroplasty.

UNLABELLED: Our goal was to analyze the results of unconstrained shoulder replacement in a large series of sequelae of proximal humeral fractures in order to validate a previously described surgical classification. In a multicenter study, we retrospectively evaluated 203 patients with sequelae of proximal humeral fractures who were treated with a nonconstrained modular and adaptable prosthesis. The mean followup was 42 months (range, 24-96 months). We identified 137 impacted fractures with humeral head collapse or necrosis (Type 1 sequelae), 25 unreducible dislocations or fracture-dislocations (Type 2), 22 nonunions of the surgical neck (Type 3), and 19 severe tuberosity malunions (Type 4). Results of nonconstrained shoulder arthroplasty for the treatment of Type 1 and Type 2 sequelae were predictably good because no greater tuberosity osteotomy was performed. The distorted anatomy was accepted, and both the prosthesis and technique were modified accordingly. Total shoulder arthroplasty yielded better results than hemiarthroplasty. Patients with Type 3 or Type 4 sequelae had poor functional results with nonconstrained arthroplasty because greater tuberosity osteotomy was needed. This study validates our fracture sequelae classification. We no longer use unconstrained prostheses in Type 3 and Type 4 fracture sequelae and propose peg bone grafting or low-profile fracture prosthesis for patients with Type 3 sequelae and reverse arthroplasty for those with Type 4 sequelae. LEVEL OF EVIDENCE: Prognostic study, level IV (case series). See Guidelines for Authors for a complete description of levels of evidence.

Adolescent↗

PubMed2005

Anatomical consequences of "open-book" pelvic ring disruption: a cadaver experimental study.

UNLABELLED: "Open-book" pelvic fractures associate a diastasis and/or a fracture of the pubic rami with a posterior pelvic disruption of the sacro-iliac joint. These uni or bilateral lesions are potentially lethal mainly due to associated injuries and massive pelvic hemorrhage. The most frequently injured arteries are parietal branch of the commune, internal or external arteries because of their proximity to the bone, the sacro-iliac joint and the inferior ligaments of the pelvis. The pelvic bone dislocation and the increase of pelvic volume facilitate blood effusion. The aim of this study was to determine, on a cadaver fracture model, the direct anatomical consequences of "open-book" pelvic fracture on the ilio-lumbar pedicle and the pelvic cavity volume. MATERIALS AND METHODS: Bilateral open-book pelvic ring injuries were created in ten non-embalmed cadaver specimens by directly disrupting the pubic symphysis, the right and the left sacro-iliac joints. Pelvic volume was determined after total pelvic exenteration. Consequences of this fracture on vascular parietal network, nervous pelvic trunk and pelvic cavity volume were studied. RESULTS: The mean volume of the pelvic cavity after complete visceral exenteration was 872.5 cm(3) (extremes 580-756 cm(3)). The average increase of pelvic volume was 20.8% after 5 cm of pubic diastasis. In all cases, because of a transversal disposition of the ilio-lumbar pedicle with regard to the sacro-iliac joint, reproduction of the open-book fracture caused a venous dilaceration of the ilio-lumbar vein in 12 cases after 5 cm of pubic diastasis (12/20=60%). No arterial dilaceration was observed on the ilio-lumbar artery, but this artery was put in tension. CONCLUSION: Open-book fractures create an increase of pelvic volume that facilitates blood diffusion from parietal pelvic vascular network. Ilio-lumbar pedicle seems to be very vulnerable in this type of fracture because of its relations to the sacro-iliac joint and its transversal disposition with regard to this joint.

Aged↗

PubMed2005

Three-dimensional culture and differentiation of human osteogenic cells in an injectable hydroxypropylmethylcellulose hydrogel.

The present work evaluates a newly developed silated hydroxypropylmethylcellulose (Si-HPMC)-based hydrogel as a scaffold for 3D culture of osteogenic cells. The pH variation at room temperature catalyzes the reticulation and self-hardening of the viscous polymer solution into a gelatine state. We designed reticulation time, final consistency and pH in order to obtain an easy handling matrice, suitable for in vitro culture and in vivo injection. Three human osteogenic cell lines and normal human osteogenic (HOST) cells were cultured in 3D inside this Si-HPMC hydrogel. We show here that osteosarcoma cells proliferate as clonogenic spheroids and that HOST colonies survive for at least 3 weeks. Mineralization assay and gene expression analysis of osteoblastic markers and cytokines, indicate that all the cells cultured in 3D into this hydrogel, exhibited a more mature differentiation status than cells cultured in monolayer on plastic. This study demonstrates that this Si-HPMC hydrogel is well suited to support osteoblastic survival, proliferation and differentiation when used as a new scaffold for 3D culture and represents also a potential basis for an innovative bone repair material.

Bone Substitutes↗