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Dirk W van Bekkum

Publications and source records attributed to Dirk W van Bekkum.

4 recordsLinked to original sources
PubMed2005

Transfer of the full-length dystrophin-coding sequence into muscle cells by a dual high-capacity hybrid viral vector with site-specific integration ability.

Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene, making it a potential target for gene therapy. There is, however, a scarcity of vectors that can accommodate the 14-kb DMD cDNA and permanently genetically correct muscle tissue in vivo or proliferating myogenic progenitors in vitro for use in autologous transplantation. Here, a dual high-capacity adenovirus-adeno-associated virus (hcAd/AAV) vector with two full-length human dystrophin-coding sequences flanked by AAV integration-enhancing elements is presented. These vectors are generated from input linear monomeric DNA molecules consisting of the Ad origin of replication and packaging signal followed by the recently identified AAV DNA integration efficiency element (p5IEE), the transgene(s) of interest, and the AAV inverted terminal repeat (ITR). After infection of producer cells with a helper Ad vector, the Ad DNA replication machinery, in concert with the AAV ITR-dependent dimerization, leads to the assembly of vector genomes with a tail-to-tail configuration that are efficiently amplified and packaged into Ad capsids. These dual hcAd/AAV hybrid vectors were used to express the dystrophin-coding sequence in rat cardiomyocytes in vitro and to restore dystrophin synthesis in the muscle tissues of mdx mice in vivo. Introduction into human cells of chimeric genomes, which contain a structure reminiscent of AAV proviral DNA, resulted in AAV Rep-dependent targeted DNA integration into the AAVS1 locus on chromosome 19. Dual hcAd/AAV hybrid vectors may thus be particularly useful to develop safe treatment modalities for diseases such as DMD that rely on efficient transfer and stable expression of large genes.

Adenoviridae↗
PubMed2004

Stem cell transplantation for autoimmune disorders. Preclinical experiments.

The clinical use of autologous stem cell transplants for the treatment of refractory severe autoimmune diseases was preceded by convincing proof of its underlying principle in animal models. The various categories of experimental autoimmune disease in laboratory rodents are briefly described here, and the rationale that was used in the selection of suitable experimental autoimmune diseases for translational research is explained. The two models that provided the bulk of the data needed for designing the initial clinical treatment protocols were adjuvant arthritis (AA) and experimental allergic encephalomyelitis (EAE), which were both induced in Buffalo rats. In this strain, AA is manifested as a chronic, progressive, systemic polyarthritis and EAE as a chronic, remitting/relapsing form of encephalomyelitis resembling multiple sclerosis. Both diseases can be cured with autologous stem cell transplantation provided that adequate conditioning is given and that the disease has not yet progressed to the stage of 'scarring'. It is basically the inflammatory stages that respond well to this therapy. The success of treatment depends on how completely the autoantigen-specific activated T-lymphocytes and memory cells are eradicated. Because of a lack of information on the nature of the autoantigens involved in human disease and on the size of those cell populations in the animal models as well as in humans, this aspect of translation is difficult. The experiments have, however, provided important guidelines. High-dose conditioning regimens yield better results than low-dose conditioning, certain conditioning agents perform better than others, and care should be taken not to reintroduce too many T-cells with the autologous graft. The clinical results obtained so far indicate a high predictive power of these two animal models, which are therefore recommended strongly for additional preclinical studies.

Animals↗
PubMedDate not supplied

Phylogenetic aspects of tissue regeneration: role of stem cells. A concise overview.

Many different forms of regeneration are known among the members of the animal kingdom. Invertebrates commonly generate new individuals by sprouting and splitting off of body parts, so that the processes of asexual reproduction and of regeneration as a response to injury can hardly be distinguished. Among the adult vertebrates, regeneration of lost body parts has become exceptional rather than the rule. However, the capacity for regeneration of tissues and for the remodeling of injured organs is much better preserved than is generally appreciated. The main reason for this misconception is the enormous variety of mechanisms for replenishment, repair, and remodeling that coexist in one and the same animal. In addition, there is a considerable variation in the response to damage inflicted by different forms of injury. Our conceptions of wound repair and tissue regeneration have been radically changed by the recent discoveries of stem cell plasticity and of dedifferentiation of supposed end cells in mice and men. Seemingly, these mechanisms should provide our bodies with near inexhaustible powers of regeneration. Yet, failures to achieve just that are among the most pressing problems of modern medicine. Apparently, counterforces have evolved that prevent the orderly replacement of lost cells. The present challenge for regenerative medicine is to unravel those barriers and find means to overcome them.

Animals↗