Experimental Study On The Effect Of PDT In Skeletal Muscle Perfusion Model Of Rabbit Thigh

ObjectiveEstablish and consummate rabbit thigh skeletal muscle perfusion model for PDT under extracorporeal circulation condition, and study the character of PDT for this rabbit model, combining with the treatment requirement during clinical extracorporeal circulation, to offer information and parameters for the application of PDT to the treatment of heart tumors, and analyze the rules of PDT effect with this model.Method &resultsPrimary part, we established the rabbit thigh skeletal muscle perfusion model according to the anatomic character of quadriceps muscle of thigh of rabbit, then tested and consummated the following in the model: 1) To determine the distribution area of perfusion fluid, we observed the diffusion of ink in this model establishment, deligated purely femoral artery or vein near knee joint. Pathology showed the muscle of experiment without ischemic damage. 3) We measured the temperature change at various tissue depth in the muscle model and the temperature effect in tissue after reduce the temperature under different power density 532nm or 632.8nm laser irradiation by temperature measurement system for biological tissue. And pathology observed the tissue in irradiation area under various conditions. The results showed temperature rise obviously at higher power density( ≥ 200mW/cm~2) and produce thermal damage, 532nm laser temperature rise more significant than 632.8nm. The tissue's temperature may be reduced by descent temperature treat with, and eliminate thermal damage. 4) We compared the influence of laser irradiation, photosensitizer, and allogenic blood perfusion on PDT effect. The results showed that the tissue injury in the rabbit thigh skeletal muscle perfusion model was a synthetic action of photosensitizer, laser irradiation etc, and photosensitizer, or laser irradiation, or allogenic bloodcardioplegic solution alone can not induce injury to the tissue.Second part, first, simulation calculated the influence factor of PDT effect on skeletal muscle under single dose perfusion by mathematic model. In theory, direct documented that when perfusion fluid is arterial blood of oxygen content major, singlet oxygen yield and singlet production are higher significantly than pure cardioplegic solution during PDT effect, and showed that under higher power density (200mW/cm~2) and higher photosensitizer concentration (160μ g /ml) , the singlet oxygen in tissue yield brief rise then fast decrease at irradiation initiation after single dose perfusion, at this time, supplement oxygen in tissue become limited factor for PDT effect. Using power density200mW/cm~2, photosensitizer concentration 120 μ g /ml ,we compared the PDT effect character under single dose crystal cardioplegic solution and single dose blood cardioplegic solution, crystal cardioplegic solution and oxygenated blood cardioplegic solution continuous perfusion and under photosensitizer 10mg/kg dose by vein injection. The result showed that under single dose crystal cardioplegic solution perfusion, oxygenated blood cardioplegic solution continuous perfusion and single dose perfusion had no effective PDT injury. Oxygenated blood cardioplegic solution continuous perfusion group induce PDT injury obviously, similar to the vein injection group.Third part, using 632.8nm laser and oxygenated blood cardioplegic solution continuous perfusion, some studies in rabbit thigh skeletal muscle perfusion model: 1) Observed the histological character immediately after irradiation, and 3 day, 1 week, 3 week, 6 week after irradiation under 200mW/cm~2 power density, and 120 μ g /ml photosensitizer concentration. The result show: the pathological change is that denaturalization muscle cell is phagocyteized absorb with inflammation reaction of major fibrous repair. 2) We compared the injury depth difference between photosensitizer concentration 120 and 240μg /ml, the results showed that injury depth was no significant difference between these two groups. 3) Both 200 mW/cm~2 or 400mW/cm~2 power density and 7.5minutes or 15minutes irradiation time matching, observe the influence of increase of power density and irradiation time on PDT injury depth. The results showed that with the energy density increasing from 90J/cm~2 (Power...