Biomedical subjects

Alberto Di Martino

Publications and source records attributed to Alberto Di Martino.

6 recordsLinked to original sources

PubMed2007

Galectin-3 expression in the intervertebral disc: a useful marker of the notochord phenotype?

STUDY DESIGN: Galectin-3 expression in rat intervertebral disc at different stages in postnatal life is evaluated. OBJECTIVE: To determine if galectin-3 expression is confined to cells of the nucleus pulposus in the postnatal rat intervertebral disc. SUMMARY OF BACKGROUND DATA: During embryonic development, the anulus fibrosus is derived from the sclerotome, whereas the nucleus pulposus is notochordal. Many authorities opine that in the postnatal disc, notochordal cells play a central role in controlling the development of degenerative disc disease. Surprisingly, unequivocal evidence supporting the existence of notochordal cells in the nucleus pulposus in postnatal life has yet to be demonstrated. Since the expression of galectin-3 is commonly used to identify notochordal cells, we evaluated its expression in tissues of the rat disc and in cultured cells. METHODS: Galectin-3 expression was studied in the nucleus pulposus and anulus fibrosus tissue of rat discs (2 days, 9 weeks, and 10 months old), and cultured cells using different biochemical and molecular biology methods. Rat sternal cartilage and cultured sternal chondrocytes were used as controls. RESULTS: Immunohistochemical studies indicated that galectin-3 was present in the nucleus pulposus and anulus fibrosus. In both discal tissues and cultured cells, studies confirmed that there was a robust expression of galectin-3 messenger ribonucleic acid and protein. Protein expression patterns were similar in neonatal, young, and mature rats. There was also evidence of intracellular and membrane expression of galectin-3 in the cultured disc cells. Finally, significant levels of galectin-3 were evident in rat sternal cartilage and cultured sternal chondrocytes. CONCLUSIONS: Results of the study indicate that galectin-3 is expressed in the neonatal, young, and mature rat disc, and its expression is not restricted to the cells of the nucleus pulposus. Because of its ubiquitous expression, this protein cannot be used as a marker of notochordal cells in the postnatal rat disc.

Aging↗

PubMed2007

Surgical management of cervical spine osteoblastomas.

The treatment of cervical spine osteoblastomas requires complex therapeutic and reconstructive strategies depending on the tumor's location, local aggressiveness, and proximity to the surrounding neurovascular structures. Despite careful removal, lesions recur in as much as 10% of patients. Preoperative embolization is useful to minimize intraoperative bleeding and decrease the relapse of vascular tumors, but its role in osteoblastoma surgery is yet to be defined. We asked whether preoperative embolization with marginal resection would lead to osteoblastoma recurrence, and whether marginal excision with reconstruction would improve neurologic symptoms. We retrospectively analyzed a consecutive series of patients with cervical spine osteoblastoma, treated by one surgeon with a combined approach of preoperative embolization, marginal excision, and spinal reconstruction. One of nine patients presented with a monoradiculopathy, whereas only two patients presented with symptomatic spinal cord compression. At followup, all patients showed neurologic improvement, no tumor relapse, and adequate bony healing. Followup imaging studies showed cervical alignment was maintained. Although we report only a small uncontrolled cohort, the data suggest preoperative embolization and a tumor-free margin are consistent with a prolonged disease-free interval or complete tumor eradication.

Adolescent↗

PubMed2006

Toward an optimum system for intervertebral disc organ culture: TGF-beta 3 enhances nucleus pulposus and anulus fibrosus survival and function through modulation of TGF-beta-R expression and ERK signaling.

STUDY DESIGN: Rat lumbar discs comprising nucleus pulposus, annulus fibrosus, and cartilaginous endplates were cultured for 1 week in a specialized media containing either TGF-beta1 or TGF-beta3. Role of TGF-beta isoforms on cell function was evaluated. OBJECTIVE: To develop an in vitro organ culture of rat intervertebral disc and evaluate effects of TGF-beta3 on disc cell function. SUMMARY OF BACKGROUND DATA: An in vitro model system is of considerable value in understanding the cell biology of the intervertebral disc. Development of a useful organ culture model would enhance understanding of disc function in health and disease. MATERIALS AND METHODS: Rat lumbar intervertebral discs were maintained in organ culture in media supplemented with TGF-beta3 or TGF-beta1 for 1 week. Tissue morphology was studied using routine histologic, histochemical and immunohistochemical techniques. Cell function was assessed by gene expression, sulfate incorporation, and Western blot analysis. RESULTS: After 1 week in culture with TGF-beta3 and TGF-beta1, the gross morphology and tissue architecture of the disc were preserved. TUNEL analysis indicated that there was no evidence of cell death in the nucleus pulposus or the anulus fibrosus. The level of Alcian blue staining in the nucleus pulposus was similar to that of the freshly isolated disc. However, when compared with TGF-beta1, TGF-beta3 elevated the expression of critical matrix genes, enhanced [S] incorporation into proteoglycans, preserved the expression of TGF-beta receptors, and decreased aggrecan turnover. There was also increased activation (phosphorylation) of ERK, a critical signaling protein. Moreover, inhibition of ERK activity, in the presence TGF-beta3, resulted in suppression of collagen Type II, aggrecan, TGF-beta-RI, TGF-beta-RII and TGF-beta-RIII mRNA expression. CONCLUSIONS: TGF-beta3 maintains the phenotype of disc cells in organ culture. It exerts this effect, in part, by elevating the levels of activated ERK1/2, which in turn regulates the expression of TGF-beta-RI and TGF-beta-RII.

Activin Receptors, Type I↗

PubMed2006

Osteogenic potential of adult human stem cells of the lumbar vertebral body and the iliac crest.

STUDY DESIGN: Marrow was aspirated from the vertebral body (VB) and iliac crest (IC) of patients undergoing lumbar spinal surgery, following an approved protocol. Progenitor cells were isolated using standard culture conditions and their osteogenic potential evaluated. OBJECTIVE: To evaluate the osteogenic potential of mesenchymal stem cells (MSCs) isolated from the bone marrow of the human VB. SUMMARY OF BACKGROUND DATA: IC marrow grafting during cervical discectomy and fusion procedure is associated with donor site morbidity. Since the VB contains marrow cells, it may be possible to circumvent this problem by using this tissue for osseous graft supplementation. However, there is paucity of information concerning the osteogenic potential of non-IC-derived progenitor cells. Herein, we address this issue. METHODS: Marrow samples from VB of patients undergoing lumbar spinal surgery were collected; marrow was also harvested from the IC. Progenitor cells were isolated and the number of colony forming unit-fibroblastic (CFU-F) determined. The osteogenic potential of the cells was characterized using biochemical and molecular biology techniques. RESULTS: Both the VB and IC marrow generated small, medium, and large sized CFU-F. Higher numbers of CFU-F were obtained from the VB marrow than the IC (P < 0.05). Progenitor cells from both anatomic sites expressed comparable levels of CD166, CD105, CD49a, and CD63. Moreover, progenitor cells from the VB exhibited an increased level of alkaline phosphatase activity. MSCs of the VB and the IC displayed similar levels of expression of Runx-2, collagen Type I, CD44, ALCAM, and ostecalcin. The level of expression of bone sialoprotein was higher in MSC from the IC than the VB. VB and IC cells mineralized their extracellular matrix to a similar extent. CONCLUSIONS: Our studies show that CFU-F frequency is higher in the marrow of the VB than the IC. Progenitor cells isolated from both sites respond in a similar manner to an osteogenic stimulus and express common immunophenotypes. Based on these findings, we propose that progenitor cells from the lumbar vertebral marrow would be suitable candidate for osseous graft supplementation in spinal fusion procedures. Studies must now be conducted using animal models to ascertain if cells of the VB are as effective as those of the IC for the fusion applications.

Bone Marrow Cells↗

PubMed2005

Nucleus pulposus replacement: basic science and indications for clinical use.

STUDY DESIGN: A critical review of available and emerging nucleus pulposus replacement implants. OBJECTIVES: To review the biomechanics, design, and clinical data of currently available and developing nucleus pulposus replacement technologies. SUMMARY OF BACKGROUND DATA: The interest in minimally invasive treatment of degenerative disc disease has grown as the technology for intervertebral motion-sparing devices continues to improve. Replacement of nucleus pulposus without anular obliteration represents a tempting alternative to spinal fusion procedures. The aim in nucleus pulposus replacement is to slow adjacent level degeneration, restore normal loads to the diseased level, and restore segmental spinal biomechanics. METHODS: A literature review of currently available biomaterials, biomechanics, and available preclinical and clinical data on nucleus pulposus replacement implants. RESULTS: New synthetic biomaterials have recently been developed to closely mimic native biomechanics during compressive loading cycles of the intervertebral disc. This, in conjunction with improved understanding of global spine biomechanics, has allowed the development of novel nucleus replacement implants. These implants are currently at different stages of preclinical and clinical investigations. CONCLUSIONS: Although some of the newly designed prosthesis have shown some promising results in preclinical studies, rigorous short- and long-term clinical evaluations will be critical in evaluating their true efficacy.

Biocompatible Materials↗

PubMed2005

Chitosan: a versatile biopolymer for orthopaedic tissue-engineering.

Current tissue engineering strategies are focused on the restoration of pathologically altered tissue architecture by transplantation of cells in combination with supportive scaffolds and biomolecules. In recent years, considerable attention has been given to chitosan (CS)-based materials and their applications in the field of orthopedic tissue engineering. Interesting characteristics that render chitosan suitable for this purpose are a minimal foreign body reaction, an intrinsic antibacterial nature, and the ability to be molded in various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. Due to its favorable gelling properties chitosan can deliver morphogenic factors and pharmaceutical agents in a controlled fashion. Its cationic nature allows it to complex DNA molecules making it an ideal candidate for gene delivery strategies. The ability to manipulate and reconstitute tissue structure and function using this material has tremendous clinical implications and is likely to play a key role in cell and gene therapies in coming years. In this paper we will review the current applications and future directions of CS in articular cartilage, intervertebral disk and bone tissue engineering.

Animals↗