OBJECTIVETo investigate the rules of proliferation of epithelial cells of sweat glands in deep partial-thickness burn wound and its transdifferentiation towards epidermal cells during healing process to explore its mechanisms.

METHODSTwenty-eight patients with limbs and trunk burn hospitalized in the Fourth People's Hospital of Taizhou City of Jiangsu Province and the Second Hospital of Shandong University from January 2004 to December 2007 were enrolled in the study. Tissue samples of deep partial-thickness burn wound (DPBW, n = 37), superficial partial-thickness burn wound (SPBW, n = 21), and normal skin (NS, n = 10) were harvested. Expressions of cytokeratin 10 (CK10), bcl-2, P63, CK14 and CK19 of epithelial cells in glandular secretory portion (GSP) in DPBW, SPBW and NS were detected with immunohistochemical double staining method.

RESULTSIn NS, CK19, CK14 and CK10 expressed in medium intensity in GSP epithelial cells, P63 and CK14 weakly expressed in basal myoepithelial cells, while no expression of bcl-2 or P63 was observed in all CK10 positive terminally differentiated cells. In SPBW, no change of the construction of GSP and above-mentioned proteins during healing process was observed. In DPBW, as examined on 7(th) post burn day (PBD), expression of P63 and bcl-2 in GSP epithelial cells was enhanced. In DPBW on 8 - 10 PBD, bcl-2, P63, CK19 and CK14 strongly positive solid island-like epithelial structure was formed by proliferation, migration and squamous epithelization of basal cells. Such structure, along with granulation tissue, migrated towards the superficial layer of wounds. The hyperplasia of squamous epithelium resulted in complete reepithelialization. In DPBW, bcl-2, CK14, CK19 and P63 still strongly expressed in hyper-proliferative epidermal basal and suprabasal layers on 13 - 30 day after healing.

CONCLUSIONSDuring the natural healing process of DPBW, monolayer epithelium (CK19 and CK10 positive) of GSP slowly develops into stratified squamous epithelium (bcl-2, P63, CK19, and CK14 positive), suggesting that the epithelial-epidermal transdifferentiation of GSP undergoes slow retrodifferentiation process of stem cells and transient amplifying cells, resulting in the imbalance between lagged growth of epithelium and the hyperplasia of granulation tissue, constituting one of the important mechanisms of disturbance in DPBW repair.