Local Photodynamic Therapy Reduces Tissue Hyperplasia in an Experimental Restenosis Model

Abstract

Local photodynamic therapy may have potential in preventing myointimal hyperplasia after angioplasty. In this study, the effect of photodynamic therapy was evaluated in an experimental model of restenosis. Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries. Animals were randomly allocated to four groups: group 1, unidirectional injury only; group 2, injury followed by local delivery of photosensitizer; group 3, injury followed by local exposure to monochromatic light; and group 4, where injury was followed by local drug delivery of photosensitizer and subsequent exposure to light (photodynamic therapy). Seven, 14 or 21 days after treatment, all experimental vessels were excised, fixed and processed for histology. An inflammatory and myoproliferative response was observed after injury in vessels from groups 1, 2 and 3. In group 4, after injury followed by photodynamic therapy, the myoproliferative response was significantly reduced. Thus, in this study, tissue hyperplasia after unidirectional injury was effectively suppressed by photodynamic therapy.

Psoralen and long wavelength ultraviolet radiation as an adjuvant therapy for prevention of intimal hyperplasia and constrictive remodeling after balloon dilation: A study in the rabbit iliac artery

“…Arterial wall injury followed by photo-activation of different sensitizers gives rise to an acellular media, after at least seven days of survival in rats and the pig [17][18][19][20]. However, in our study, arterial wall injury without photoactivation of the sensitizer also gives rise to a large amount of acellularity of the media at two days of survival, which is in contrast with observations in the rabbit after a same survival period [21].…”

“…PUVA-therapy has been reported to inhibit intimal hyperplasia and luminal narrowing after 14 days of survival [14]. In contrast to the latter study and a number of PDT studies [17][18][19][20], our study does not support the combination of a photosensitizer and subsequent activation by light to be precautionary for the induction of intimal hyperplasia and luminal narrowing. This observation is in agreement with another study using pig coronary arteries [28].…”

“…In unpublished pilot experiments, we have demonstrated that covalent interactions between 8-MOP and the target cell DNA could be detected after UVA irradiation in a dosedependent manner; this was accomplished with the 8G1 antibody, kindly supplied by Regina M. Santella [23]. The mechanism of covalent interaction, however, is different from the singlet oxygen mediated photodynamic therapy (PDT) mechanism, that is aimed at the destruction of the target cells, as used in the above mentioned studies [17][18][19][20].…”

Photodynamic Therapy of Atherosclerosis Using YAG-OPO Laser and Porfimer Sodium, and Comparison With Using Argon-Dye Laser

“…There have been few reports on the efficacy of PDT in the treatment of atheroma, [11][12][13][14][15][16][17][18][19][20][21][22][23] and we were unable to find any reports using the YAG-OPO laser. In this present study we conducted PDT using the YAG-OPO laser in an intravascular approach on atherosclerotic rabbit aortas, investigating the regression effect on hypertrophic intima.…”

Photoangioplasty

“…In addition, both short-and long-term benefits of PDT have been demonstrated. 45,52 In another study of PDT in a balloon-injured rodent arterial model, the media remained acellular for several weeks to months, and intimal hyperplasia did not occur. 6 Although endothelial regeneration occurred by 2 weeks, SMCs failed to repopulate the media.…”