Cytokines and osteolysis around total hip prostheses

The aim of this work is to assess the correlation between the osteolysis around the prosthesis and the presence of cytokines favouring inflammation in the tissues at the interface between loosened prosthesis and bone. In this study, twenty-nine patients that underwent revision surgery were examined. Bioptic samples were collected at the interface between bone and implant both at the stem and socket level. Semiquantitative immunohistochemistry was performed to detect interleukin 1 alpha, interleukin 1 beta, interleukin 6 and tumour necrosis factor, cytokines that directly cause bone resorption and indirectly induce synthesis of other bone resorbing cytokines. Wear particles were identified and quantified by light microscopy. Radiographic evidence for osteolysis was scored by the Engh and Bobyn score. In tissues collected at the interface, the percentage of cells positive to IL1, IL6 and particularly to TNF increased in relation to the tissues collected at the interface with stable components. The cells occurring in the new capsule do not secrete cytokines in quantities that can be related to severity of wear. Cemented prostheses showed higher incidence of severe osteolysis, and higher levels of cytokines. It can be concluded that TNF, and to a lesser extent IL1 and IL6, are positively related to the severity of osteolysis around the prosthesis and therefore a pharmacological treatment can be hypothesized with anti-inflammatory or anti-cytokine drugs in order to limit or to avoid prosthesis loosening.     

Design and synthesis of chiral peptidic nucleic acids

Due to the increasing interest in the use ofoligonucleotide analogues as antisense and antigenedrugs, we designed a chiral analogue constituted of apeptidic frame bearing nucleobases in suitablepositions (C-PNA). We recently reported the synthesisof four nonnatural -amino acids with the DNAbases in the lateral chain. In this paper we presentan improved synthesis of the Fmoc monomers and theirpolymerisation to polypeptidic oligonucleotideanalogues using a modification of the standardprotocol for solid phase peptide synthesis.     

Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells

The nonadherent (NA) population of bone-marrow-derived mononuclear cells (MNC) has been demonstrated to be a source of osteogenic precursors in addition to the plastic-adherent mesenchymal stromal cells (MSC). In the current study, two subpopulations of late adherent (LA) osteoprogenitors were obtained by subsequent replating of NA cells, and their phenotypic, functional, and molecular properties were compared with those of early adherent (EA) MSC. Approximately 35% of MNC were LA cells, and they acquired a homogeneous expression of MSC antigens later than EA cells. In EA-MSC, the alkaline phosphatase (ALP) activity increased significantly from time of seeding to the first confluence, whereas in LA cells it raised later, after the addition of mineralization medium. All subpopulations were able to produce type I collagen and to deposit extracellular matrix with organized collagen fibrils. The proportion of large colonies with more than 50% of ALP positive cells as well as the calcium content was higher in LA than in EA cells. Molecular analysis highlighted the upregulation of bone-related genes in LA-MSC, especially after the addition of mineralization medium. Our results confirm that bone marrow contains LA osteoprogenitors which exhibit a delay in the differentiation process, despite an osteogenic potential similar to or better than EA-MSC. LA cells represent a reservoir of osteoprogenitors to be recruited to gain an adequate bone tissue repair and regeneration when a depletion of the most differentiated component occurs. Bone tissue engineering and cell therapy strategies could take advantage of LA cells, since an adequate amount of osteogenic MSCs may be obtained while avoiding bone marrow manipulation and cell culture expansion.     

Design and synthesis of chiral peptidic nucleic acids

Summary Due to the increasing interest in the use of oligonucleotide analogues as antisense and antigene drugs, we designed a chiral analogue constituted of a peptidic frame bearing nucleobases in suitable positions (C-PNA). We recently reported the synthesis of four nonnatural α-amino acids with the DNA bases in the lateral chain. In this paper we present an improved synthesis of the Fmoc monomers and their polymerisation to polypeptidic oligonucleotide analogues using a modification of the standard protocol for solid phase peptide synthesis.