Invited Discussion

This study presents transplantation of groin flaps from Wistar-to-Wistar rats and secondary re-transplantation to the same Wistar rats after a period of time ranging from 2 to 8 days. The concept is interesting, and related to the preservation of the amputated parts of the first animal in what serves as the preserver (Pr-rat), for a period of time necessary for the preparation of the auto-donor rat.

The Wistar-to-Wistar transplantation model is described by the authors as an isopreservation model. If it is really an isopreservation transplantation, it is difficult to perceive why the authors would use immunosuppression in such a model, in which there would be acceptance without any rejection following transplantation. The Wistar rats are outbred rats and, as such, do not carry known MHC antigens; they are probably not appropriate animals in which to study transplantation events.

Of 17 groin flaps which were transplanted, seven were lost due to thrombosis and failure of the microsurgical procedures. This is a relatively high percentage rate of the loss of flaps in a ``normal isograft'' transplantation model (over 41 percent).

Furthermore, the authors do not give a rationale for using Prednisolone and FK506 in this experimental design; nor do they explain the rationale for the dosage of immunosuppressive therapy. There is also a lack of uniformity in the length of time for preservation of the groin flap in the Pr-rat, and for a rationale for ``long-time'' or ``short-time'' preservation. A more serious critique of this model is that it has little clinical application. It would be applicable in individuals who, according to this design, would be willing to be submitted to immunosuppression for a certain period of time, in order to preserve tissue which belongs to a donor who was not immunosuppressed, knowing that there is only about a 50 percent chance for tissue salvage in this model.

The introduction does not explain why isopreservation or, as further discussed, allopreservation were used, instead of autopreservation in this model. The discussion section is only partially relevant to the presented model; quite a few statements which are intended to support the study are related to allograft transplantation. In addition, one page of the discussion relates to the presentation of the results, rather than to the discussion of the results.

The idea of preservation of tissue transfer to a secondary recipient is intriguing. However, I would have appreciated more support for the concept in the study design, presentation, and development, as well as figures which were clearer and more aesthetic. I question the implication that the isograft transplantation should be treated with immunosuppressive therapy, and could potentially reject genetically identical tissue. The outbred animal model (Wistar-to-Wistar) chosen for transplantation makes it difficult to interpret the presented results, since each heterozygous animals differs in immunologic structure, which is not well-defined. I would suggest that the authors check their hypothesis on the inbred strain of rats with known MHC antigens, and compare auto-, iso-, and allo-transplantations in an immunologically-defined experimental design.