Bone-targeting AAV-mediated silencing of Schnurri-3 prevents bone loss in osteoporosis

RNAi-based bone anabolic gene therapy has demonstrated initial success, but many practical challenges are still unmet. Here, we demonstrate that a recombinant adeno-associated virus 9 (rAAV9) is highly effective for transducing osteoblast lineage cells in the bone. The adaptor protein Schnurri-3 (SHN3) is a promising therapeutic target for osteoporosis, as deletion of shn3 prevents bone loss in osteoporotic mice and short-term inhibition of shn3 in adult mice increases bone mass. Accordingly, systemic and direct joint administration of an rAAV9 vector carrying an artificial-microRNA that targets shn3 (rAAV9-amiR-shn3) in mice markedly enhanced bone formation via augmented osteoblast activity. Additionally, systemic delivery of rAAV9-amiR-shn3 in osteoporotic mice counteracted bone loss and enhanced bone mechanical properties. Finally, we rationally designed a capsid that exhibits improved specificity to bone by grafting the bone-targeting peptide motif (AspSerSer)6 onto the AAV9-VP2 capsid protein. Collectively, our results identify a bone-targeting rAAV-mediated gene therapy for osteoporosis.

No influence of collagenous proteins of Achilles tendon, skin and cartilage on the virus-inactivating efficacy of peracetic acid–ethanol

The risk of transmitting human pathogenic viruses via allogeneic musculoskeletal tissue transplants is a problem requiring effective inactivation procedures. Virus safety of bone transplants was achieved using peracetic acid (PAA)-ethanol sterilisation. Proteins are known to have an adverse effect on the virus-inactivating capacity of PAA. Therefore we investigated virus inactivation by PAA in collagenous tissues. Achilles tendon, skin and cartilage were cut into small pieces, lyophilised and contaminated with pseudorabies virus (PRV) or porcine parvovirus (PPV). The inactivating capacity of PAA-ethanol was investigated by determining virus titres in the supernatant or the tissue pellet at different time-points. In all virus-contaminated tissue samples treatment for 10 min with PAA-ethanol resulted in titre reductions by a factor of >10(3). PRV was rapidly inactivated below the detection limit (< or =2.8 x 10(1) TCID(50)/ml). After 240 min a reduction by a factor of >10(4) was obtained for PPV in all samples, but a residual infectivity remained. Collagenous proteins of Achilles tendon, skin and cartilage had no adverse effect on the virus-inactivating capacity of PAA. PAA-ethanol used in the production process at the Charité tissue bank can therefore be recommended for treatment of non-osseous musculoskeletal tissues.

Regulation of the long terminal repeat in visna virus by a transcription factor related to the AML/PEBP2/CBF superfamily

The long terminal repeats of maedi visna virus strain 1514 contain a consensus AP-1 binding site which has been shown to be important in controlling virus transcription. However, this consensus site is absent in strain EV-1. Here, we have compared the ability of oligonucleotides corresponding to LTR sequences from EV-1 with those from 1514 to bind transcription factors in competitive gel retardation assays and activate reporter gene expression. The experiments demonstrated no observable binding of AP-1 to the EV-1-derived sequences and significant differences in the abilities of the 1514 and EV-1 sequences to activate transcription. However, both viral sequences interacted with a second, previously undetected, transcription factor. This factor gave specific gel shifts which were competed by an oligonucleotide containing the consensus sequence for the AML/PEBP2/CBF family of transcriptional factors, but not by control AP-1 or OCT-1 oligonucleotides. The factor was therefore denoted AML (vis). A second AML (vis) site, noted upstream of the TATA box proximal AP-1 site, gave single shifts which were competed by the downstream AML (vis) oligonucleotide. Both sites were functional in transfection assays. In gel shift retardation assays, polyclonal antisera directed against known runt domain proteins were able to supershift part of the AML (vis) binding activity in nuclear extracts from physiologically relevant cell types. The results thus suggest that the AML (vis) binding factor belongs to the AML/PEBP2/CBF family of transcription factors and may be important in controlling virus replication in these and other strains of ruminant lentiviruses.

Influence of chemical allograft preservation procedures on the human immunodeficiency virus

Since chemically preserved allogenic transplants have an established place in reconstructive procedures, the possibility of transferring the human immunodeficiency virus (HIV) with these transplants has been intensively discussed. In this study the authors obtained brain and spleen samples from six HIV-infected cadavers and preserved them with Merthiolate, Cialit, and formaldehyde. After preservation, the tissues were examined for proviral HIV-1 DNA (gag, pol, env) using the polymerase chain reaction. Proviral sequences were clearly demonstrated after the preservation procedure. The results of this study indicate that HIV remains in tissues that have been treated with Merthiolate, formaldehyde, or Cialit. Further investigations are necessary to determine if the virus is in an inactivated or activated form. It can be concluded that, because of the possible transmission of HIV by chemically preserved homografts, serologic screening of donors should be mandatory.

[In vitro cultivation of human chondrocytes using autologous human serum supplemented culture medium: minimizing possible risk of infection with pathogens of prion diseases]

BACKGROUND

The in vitro engineering of autologous transplant might play an important role in reconstructive surgery in the near future. The amplification of isolated cells is an important part of the engineering. Because of the use of fetal calf serum (fcs) in the cellculture, there is a potential risk of transmission of prion diseases. The aim of this study was to evaluate a way of amplifying chondrocytes with autologous human serum instead of fcs and to compare the rates of proliferation.

METHODS

For this purpose the isolated chondrocytes were cultured using complete medium, with 10% fcs or 10% autologous human serum being added to the medium.

RESULTS

The experiments show that a culture with complete medium and autologous human serum allows a 150 to 300fold increase in the number of cells after 40 days of culture and the proliferation is up to 3fold higher than in cultures using fcs.

DISCUSSION

Chondrocytes can be stimulated by autologous human serum to proliferate. It is possible to avoid fcs in the culture of chondrocytes and to minimize the risk of an infection with prions.

Histologic and immunocytochemical characterization of canine distemper-associated metaphyseal bone lesions in young dogs following experimental infection

The proximal metaphyses of the humerus of weanling gnotobiotic dogs experimentally infected with canine distemper virus (CDV) were investigated histologically and immunocytochemically between 4 and 41 days after infection. Viral antigen was demonstrated in hematopoietic marrow and bone cells at postinfection day (PID) 5 and PID 7, respectively. Between PID 8 and 27, CDV antigen was abundantly present in marrow cells, osteoclasts, and osteoblasts and less frequently in osteocytes. Immunopositive cells in both osseous tissues and bone marrow declined between PID 29 and PID 36 and were absent by PID 41. Chondrocytes of the growth plate were negative for viral antigen throughout the observation period. In bone, viral antigen was more frequently observed in bone cells of the primary spongiosa than in the secondary spongiosa. There was a strong correlation between occurrence of CDV antigen and osseous changes. Associated metaphyseal bone lesions were mild and most prominent between PID 8 and PID 32. Lesions consisted of necrosis of osteoclasts, which was associated with subsequent persistence of the primary spongiosa (growth retardation lattice). Atrophy and necrosis of osteoblasts and marrow cells were also noted. Infection of metaphyseal bone cells appears to be common in young dogs with experimental systemic distemper. Bone cell infection is preceded by infection of marrow cells, and infected bone cells may experience degeneration and necrosis. This subtle viral effect may result in defects in bone modeling in CDV-infected dogs.

Absence of HIV-1 DNA in cartilage from HIV-positive patients

Human immunodeficiency virus (HIV) infections are mainly transferred by blood, semen or organ transplantations. Since allogenic transplants have an established place in reconstructive surgery, the possibility of transferring HIV with such transplants has been a subject of much concern. Postmortem cartilage samples were obtained from eight HIV-infected patients and examined using the polymerase chain reaction in order to detect proviral HIV-1 DNA (gag, pol, env). Blood, brain and spleen samples were also obtained and used as positive controls. Results showed that no cartilage sample contained any HIV-DNA, whereas proviral sequences were clearly demonstrated in perichondrium from six patients. These findings indicate that HIV is not present in cartilage of HIV-infected patients, making HIV transmission through cartilage grafting improbable when transplants from HIV-negative donors are used.