Case Report: Human Tracheal Transplantation Undergoes Progressive Reepithelialization Over Time

Area of Science:

• Regenerative Medicine
• Transplantation Biology
• Histopathology

Background:

• Tracheal transplantation offers a solution for long-segment tracheal defects.
• Vascularized single-staged tracheal transplantation was successfully performed.
• The role of ciliated epithelium in mucociliary clearance is crucial for tracheal function.

Purpose of the Study:

• To examine the histological changes in the first single-staged human tracheal transplant.
• To assess the reepithelialization process and epithelial recovery post-transplantation.

Main Methods:

• Serial endoscopic biopsies of the tracheal mucosa were collected post-transplantation.
• Histological analysis included hematoxylin and eosin staining, electron microscopy, and immunohistochemistry.

Main Results:

• Initial loss of ciliated and seromucinous cells observed one week post-transplant.
• Epithelial recovery began by two weeks, with variations between anastomosis and midgraft sites.
• Squamous metaplasia noted in the midgraft, while anastomosis showed epithelial proliferation with early ciliated cells.
• Normal ciliated epithelium and mucous cells reappeared over time without chronic inflammation.

Conclusions:

• The tracheal allograft successfully regenerated normal respiratory epithelium after ischemic injury.
• Distinct reepithelialization mechanisms may exist at the anastomosis (recipient cell migration) and midgraft (donor cell proliferation).
• Understanding these mechanisms is vital for optimizing tracheal transplant outcomes.