Local tissue reaction to implantation of biodegradable suture materials.

Morphological changes in tissues adjacent to the implant were studied 1, 2, 6, and 12 months after implantation of biodegradable suture materials (catgut thread, DemeTECH polyfilament thread, and Surgilactin monofilament thread) into subcutaneous fat of rats. Tissue reaction to implantation of different suture materials developed as usual in response to a wound process and to a foreign body. By the end of month 1. the stage of traumatic perifocal inflammation was replaced in all groups by the proliferative phase with formation of new vessels and connective tissue. A trend to reduction of the productive inflammation activity from month 1 to month 12 was noted. Complete degeneration of the material after 12 months with complete recovery of the histoarchitecture of the adjacent tissues (restitution) was detected only after implantation of DemeTECH polyfilament thread.

Reaction of rat tissues to implantation of lactic acid-based biodegradable polymer.

Polylactide degradation processes after its implantation into the subcutaneous fat of rats were studied by microscopy. After implantation polylactide was encapsulated in connective tissue. If a fragment of polylactide had sharp edges, injuring the tissue, a thick capsule formed with pronounced inflammatory infiltration and sclerosis of adjacent tissues. If the implant had no sharp edges, the capsule was thin and the level of inflammation the minimum. Foreign body giant cells were found in the capsule and near it in all cases. The activity of the inflammatory process gradually reduced over 6 months. The intensity of inflammation sharply increased by the 12th month after implantation, when activity of phagocyte enzyme and deformation by the capsule led to fragmentation or liquefaction of polylactide.

[Tissue reactions to the use of implants manufactured from lactic acid polymers].

Recent literature on the morphological results of the application of polymers produced from lactic acid (polylactides--PLA), contains a plethora of experimental and clinical data on the efficiency and safety of their use for the medico-biological purposes. However, the question on the actual rate of biological disintegration of PLA materials remains unanswered. There are conflicting views on the inflammatory reaction ranging from a complete negation of an inflammatory response to PLA implantation up to the reports describing the expressed aseptic inflammatory reactions caused by presence of this material in tissues. Some researchers report the total absence of the foreign-body reactions to this class of implants, while some others indicate the obligatory formation of the foreign-body giant cells. Further research is necessary to precisely predict degradation processes of and to detect all the potential risks associated with the use of PLA-based materials.

[Morphological tissue changes after the implantation of a biodegradable material on collagen basis].

The objective of this study was to examine the peculiarities of tissue reactions during the degradation of "Collost" bioplastic material on the collagen basis with completely preserved fibrous structure, after its implantation into the bone tissue defect. The defect in bone tissue sized 1-2 mm x 3-5 mm was created in tibial condyle. The study was performed on 24 Wistar rats using light microscopic methods. The tissue reactions were studied at different time intervals (1, 2, 6 and 12 months) after the implantation of collagenic material. It was found that after the implantation, the material became impregnated with blood, and due to fibrin, densely adhered to the damaged tissues. Further, the cells were found to migrate along the blood clot into its depth from the surrounding tissues. These were primarily the fibroblasts which were located in a network of fibers and started to absorb collagen from a surrounding material and to synthesize new collagen. Gradually, the collagenic material became similar to a cell-containing network. The volume of the newly synthesized collagen increased, and after some time all the foreign material was absorbed by fibroblasts and replaced with connective tissue. After 1 year, a large "Collost" fragment was completely degraded and replaced by loose connective tissue. The implantation of a collagenic material did not stimulate the formation of a delimiting connective tissue capsule

[Peculiarities of tissue reactions during resorption of biodegradable suture materials].

The reaction of the surrounding tissues to the implantation of biodegradable suture materials (plain catgut threads, DemeTECH polyglactin 910, Surgilactin--polyglactin 910) into the subcutaneous adipose tissue of rats, was studied using light microscopy 1, 2, 6 and 12 months after grafting. It was shown that the tissue reactions to implantation of different biodegradable suture materials followed the general pattern characteristic of wound healing and foreign body reaction. By the first month of observation, in all the animal groups, the stage of traumatic perifocal inflammation was replaced by a proliferative phase with the new growth of the blood vessels and connective tissue. In all the animal groups, there was a trend to reduction of productive inflammation activity from the 1st month till the 12th month. By the 12th month the total degeneration of the material with full recovery of structure of surrounding tissues (restitution) was recorded only after the implantation of polyglactin 910 (DemeTECH).