Faculty Bibliography

BACKGROUND: The role of cytokines in tumor regression is now well established. The major limitation for the clinical use of cytokines is the lack of a simple and effective protocol for the local and sustained delivery of cytokines to the tumor milieu. This study reports suppression of human head and neck squamous cell carcinoma (HNSCC) by human peripheral blood lymphocytes (HuPBL) following local, sustained delivery of interleukin-12 (IL-12) to tumors with biodegradable microspheres in a human/SCID mouse chimeric model. Materials and Methods Nondisrupted biopsy pieces (120 mg) of primary HNSCC were implanted s.c. into severe combined immunodeficient (SCID) mice and were expanded by serial passage in mice. Tumors were then titrated with different doses of allogeneic HuPBL by coengraftment of tumor pieces and HuPBL into the subcutis of SCID mice to determine whether the HuPBL possessed antitumor activity (the SCID/Winn model). The lymphocyte subsets that were responsible for the suppression of tumor engraftment were identified by selective depletion of the CD4+, CD8+, and CD56+ cells from the HuPBL prior to engraftment into mice. Attempts were then made to augment the antitumor activity of the HuPBL either by repeated intralesional bolus injections of recombinant human IL-12 (0.5 &mgr;g x 10 doses) or with a single dose of IL-12-loaded microspheres ( approximately 1.65 &mgr;g IL-12/mg microspheres, 2 mg microspheres/mouse). RESULTS: Successful engraftment of HNSCC was observed in 12 of 19 different patient samples. Normal histological architecture of tumor was maintained up to four serial passages in the SCID mice. After the first tumor engraftment, but not in subsequent passages, human immunoglobulin produced by plasma cells present in the tumor infiltrating lymphocyte population was detected in the mouse sera. Allogeneic human PBL displayed antitumor cytotoxic activity in a cell dose-dependent fashion when coengrafted with the tumors passaged in SCID mice. Lymphocyte subset depletion studies established that tumor suppression was dependent on both the CD8+ T lymphocytes and the CD56+ natural killer cells. Treatment of tumors with a single intralesional injection of IL-12-loaded microspheres was highly effective, resulting in the complete suppression of tumor engraftment in 50% of the mice. In contrast, treatment of tumors with repeated bolus IL-12 injections suppressed tumor engraftment only transiently and did not result in complete tumor rejection in any of the mice. CONCLUSION: The coengraftment of HNSCC and allogeneic lymphocytes into SCID mice provides a viable model with which to evaluate immunotherapeutic strategies for human cancer. The use of biodegradable microspheres for local sustained delivery of cytokines to augment lymphocyte mediated antitumor immunity within the tumor microenvironment provides a safer and simpler alternative to current cytokine immunotherapy protocols.

BACKGROUND: Microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions. Despite the availability of various mechanical anastomotic coupling systems for human clinical use during the last 8 years, reported clinical series remain rare. OBJECTIVE: To describe a clinical experience in applying a mechanical microvascular anastomotic coupling device (MACD) to end-to-side anastomotic configurations in head and neck free-flap reconstruction. METHODS: The MACD is a readily available high-density polyethylene ring-stainless steel pin system that has been found to be highly effective in clinical studies of end-to-end arterial and venous anastomosis and in laboratory studies of end-to-side anastomosis of rabbit arteries. RESULTS: Thirty-seven end-to-side venous anastomoses were attempted, of which 33 (89%) were completed. Of these, 9 patients had critical anastomoses (only 1 venous anastomosis per patient). In patients undergoing parallel venous anastomoses, 6 had both anastomoses performed using the MACD; in the remaining 12 patients, 1 of the anastomoses was performed using the MACD. A variety of donor flaps and clinical contexts were encountered. Flap survival in the MACD series was 100%. Four anastomoses were converted to conventional suture technique intraoperatively. CONCLUSIONS: The MACD is well suited to end-to-side venous anastomosis when carefully and selectively used by experienced microvascular surgeons. The most common clinical situation requiring this configuration and technique was the lack of ipsilateral recipient veins for end-to-end anastomosis or a ligated internal jugular vein stump that required this approach for device application. Previous radiation therapy does not appear to be a contraindication to its use