Reconstructive Microsurgery

Preliminary experience using the VITOM-3D system for microvascular anastomosis in DIEP free flap breast reconstruction

Free tissue transfer has become routine practice in modern plastic surgery. The technique permits surgeons the flexibility to transfer the most suitable tissue for reconstruction. This has become possible largely due to the continued advances in microscope technology. There are however several drawbacks with even the newest traditional operating microscopes. They are usually large, heavy and although highly adjustable often require surgeons to adopt an unnatural and uncomfortable position which many of us have simply learned to live with. We describe the use of a new high-definition 3D camera system (Stortz VITOM 3D) in place of a traditional microscope to perform DIEP flap breast reconstructions in two patients. The use of this equipment has been described in other surgical specialities where a number of its benefits, including improved ergonomics for surgical team, have been highlighted. We explore the specific benefits and considerations for its use in free flap reconstruction of the breast .

Principles of implant-based reconstruction and rehabilitation of craniofacial defects

The final stages of reconstruction following craniofacial trauma or tumor resection often involve the fitting of prostheses. Development of osseointegrated implants for retention of prostheses has improved function and aesthetic outcome. Placement of osseointegrated implants requires coordinated care from multiple specialists and a lifetime commitment of the patient. The workup and surgical treatment algorithms for placement of intraoral compared with extraoral implants are discussed. The quality and quantity of bone available are the most important factors influencing design and placement. The long-term retention of implants is influenced by implant site, local tissue bed preparation, and hygiene. Osseointegrated implants are a part of the complete rehabilitation of patients with craniomaxillofacial defects. Although final fitting and maintenance of prostheses is completed by prosthodontists and patients, successful placement and preservation of implants is affected largely by the plan set forth by the reconstructive surgeon.

Tissue engineering using autologous microcirculatory beds as vascularized bioscaffolds

Classic tissue engineering paradigms are limited by the incorporation of a functional vasculature and a reliable means for reimplantation into the host circulation. We have developed a novel approach to overcome these obstacles using autologous explanted microcirculatory beds (EMBs) as bioscaffolds for engineering complex three-dimensional constructs. In this study, EMBs consisting of an afferent artery, capillary beds, efferent vein, and surrounding parenchymal tissue are explanted and maintained for 24 h ex vivo in a bioreactor that preserves EMB viability and function. Given the rapidly advancing field of stem cell biology, EMBs were subsequently seeded with three distinct stem cell populations, multipotent adult progenitor cells (MAPCs), and bone marrow and adipose tissue-derived mesenchymal stem cells (MSCs). We demonstrate MAPCs, as well as MSCs, are able to egress from the microcirculation into the parenchymal space, forming proliferative clusters. Likewise, human adipose tissue-derived MSCs were also found to egress from the vasculature and seed into the EMBs, suggesting feasibility of this technology for clinical applications. We further demonstrate that MSCs can be transfected to express a luciferase protein and continue to remain viable and maintain luciferase expression in vivo. By using the vascular network of EMBs, EMBs can be perfused ex vivo and seeded with stem cells, which can potentially be directed to differentiate into neo-organs or transfected to replace failing organs and deficient proteins.

[Experimental and clinical experience of composite tissues allotransplantation in reconstructive surgery]

Composite tissue allotransplantation (CTA) is a new concept in reconstructive surgery to improve major physical defects with no current solution. Although not a life-saving procedure, tissue replacement by CTA offers great potential for improving quality of life but relies on lifelong immunotherapy. This new practice has become achievable with the refinement of microsurgical techniques, with experience gained from limb and scalp replantations, with the development of organ transplantation and the release of new immunosuppressive drugs. Experimental and clinical research made it possible. The first human cases of CTA proved the reality and the feasibility of the concept. While the early functional results of these allografts are encouraging, they will need to be assessed in the long-term, and development of less toxic - more efficient immonu-suppressive drugs will be a permanent requisite to the broadening of CTA. Although long-term outcome and potential adverse effects of chronic immunosuppression remain uncertain, as for organ transplantation, CTA is already a potential solution for some highly selected patients carrying physical disabilities such as large facial defects and bilateral hand amputation.

Induction of heat shock proteins in a rat composite tissue allotransplantation model of acute rejection

BACKGROUND

Clinical cases of composite tissue allotransplantation have been reported, but the exact mechanisms of allograft rejection remain unclear. The current study examined the possible involvement of heat shock proteins in major histocompatibility complex-compatible minor-mismatch composite tissue allotransplantation rejection.

METHODS

Allotransplantation (Fisher 344 to Lewis) and isotransplantation (Lewis to Lewis) of rat lower extremities were performed. Temporal profiles of 70-kDa and 60-kDa heat shock proteins (heat shock protein 70 and heat shock protein 60) were conducted by quantitative Western blot analysis and immunohistochemistry. Analyses were performed immediately after reperfusion (day 0) and on postoperative days 1, 3, 7, and 12 (n = 5 for quantitative Western blot analysis and n = 5 for immunohistochemistry).

RESULTS

The expression levels of the inducible forms of heat shock protein 70 and heat shock protein 60 were uniformly and significantly augmented until postoperative day 7 in the allografts, compared with the isografts (p < 0.001 for each protein). Immunoreactivities to heat shock protein 70 and heat shock protein 60 in keratinocytes, hair follicular cells, and endothelial cells of the subdermal vascular plexus were enhanced in the allografts early on postoperative day 1. Positive staining of hair follicles extended to deeper parts of the hair follicles and hair bulbs in the allografts on postoperative day 3. Although dendritic cells were positive for both heat shock protein 70 and heat shock protein 60, infiltrating lymphocytes were positive only for heat shock protein 60.

CONCLUSIONS

These results suggest the possible involvement of heat shock proteins in the process of major histocompatibility complex-compatible minor-mismatch composite tissue allotransplantation rejection. Thus, modulation of the function of heat shock proteins might be an important therapeutic option for improving the outcome of minor-mismatch allografts.

A Cadaver Study in Preparation for Facial Allograft Transplantation in Humans: Part II. Mock Facial Transplantation

BACKGROUND

The authors have performed mock facial transplantation by harvesting total facial-scalp flaps from donors and transferring them to recipient cadavers.

METHODS

A total of 10 fresh human cadavers were dissected. In the donor, the authors have measured the time of facial-scalp flap harvesting, and the length of the arterial and venous pedicles and sensory nerves that were included in the facial flaps. In the recipient, the authors have evaluated the time of facial skin harvest as a monobloc full-thickness graft, the anchoring regions for the inset of the donor facial flaps, and the time sequences for the vascular pedicle anastomoses and nerve coaptations.

RESULTS

In the donor cadaver, the mean harvesting time of the total facial-scalp flap harvest was 235.62 +/- 21.94 minutes. The mean length of the supraorbital, infraorbital, mental, and great auricular nerves was 1.5 +/- 0.15, 2.46 +/- 0.25, 3.02 +/- 0.31, and 6.11 +/- 0.42 cm, respectively. The mean length of the external carotid artery, the facial vein, and external jugular vein was 5 +/- 0.32, 3.15 +/- 0.32, and 5.78 +/- 0.5 cm, respectively. In the recipient cadaver, the mean harvesting time of facial skin as a monobloc full-thickness graft was 47.5 +/- 3.53 minutes. The mean time for the preparation of the arterial and venous pedicles and sensory nerves for the future anastomoses and coaptation was 30 +/- 0 minutes. The mean time for facial flap anchoring was 22.5 +/- 3.53 minutes. The total mean time of facial mock transplantation without vessels and nerve repair was 320 +/- 7.07 minutes (5 hours 20 minutes).

CONCLUSION

Based on anatomical dissections in this cadaver study, the authors have estimated the time and sequence of facial flap harvest and inset to mimic the clinical scenario of the facial transplantation procedure.