Research Alert


Treatments involving stem cell (SC) usage represent novel and potentially interesting alternatives in facial nerve reanimation. Current literature includes the use of SC in animal model studies to promote graft survival by enhancing nerve fiber growth, spreading, myelinization, in addition to limiting fibrotic degeneration after surgery. However, the effectiveness of the clinical use of SC in facial nerve reanimation has not been clarified yet.


To investigate the histological, neurophysiological, and functional outcomes in facial reanimation using SC, compared to autograft.


Our study is a systematic review of the literature, consistently conducted according to the preferred reporting items for systematic reviews and meta-analyses statement guidelines. The review question was: In facial nerve reanimation on rats, has the use of stem cells revealed as effective when compared to autograft, in terms of histological, neurophysiological, and functional outcomes? Random-effect meta-analysis was conducted on histological and neurophysiological data from the included comparative studies.


After screening 148 manuscript, five papers were included in our study. 43 subjects were included in the SC group, while 40 in the autograft group. The meta-analysis showed no significative differences between the two groups in terms of myelin thickness [CI: -0.10 (-0.20, 0.00); I2 = 29%; P = 0.06], nerve fibers diameter [CI: 0.72 (-0.93, 3.36); I2 = 72%; P = 0.6], compound muscle action potential amplitude [CI: 1.59 (0.59, 3.77); I2 = 89%; P = 0.15] and latency [CI: 0.66 (-1.01, 2.32); I2 = 67%; P = 0.44]. The mean axonal diameter was higher in the autograft group [CI: 0.94 (0.60, 1.27); I2 = 0%; P ≤ 0.001].


The role of stem cells in facial reanimation is still relatively poorly studied, in animal models, and available results should not discourage their use in future studies on human subjects.

Key Words: Facial nerve, Palsy, Reanimation, Coaptation, Stem cells, Nerve fibers, Functional outcome


Core Tip: Our meta-analysis of studies comparing the use of autograft and stem cells for facial nerve reanimation in rats suggest that there appears to be no advantages in favor of stem cells, according to the evaluated histological and neurophysiological outcomes. Stem cell treatments have proven to be an interesting and viable option in numerous fields of surgery that have vast supporting scientific and clinically applicable literature. The role of stem cells in facial reanimation is still relatively new and poorly studied due to the liming nature and number of studies carried out exclusively in animal models.

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