Chondrocyte-specific Smad4 gene conditional knockout results in hearing loss and inner ear malformation in mice.

Smad4 is the central intracellular mediator of transforming growth factor-beta (TGF-beta) signaling, which plays crucial roles in tissue regeneration, cell differentiation, embryonic development, and regulation of the immune system. Conventional Smad4 gene knockout results in embryonic lethality, precluding its use in studies of the role of Smad4 in inner ear development. We used chondrocyte-specific Smad4 knockout mice (Smad4Co/Co) to investigate the function of Smad4 in inner ear development.

Smad5 haploinsufficiency leads to hair cell and hearing loss.

The Smads are a group of related intracellular proteins critical for transmitting the signals to the nucleus from the transforming growth factor-beta superfamily at the cell surface. Knockout of the Smad5 is embryonic lethal. However, the Smad5 knockout of single allele (+/-) could survive.

[Overexpression of Hath1 induces production of hair cell-like cells in greater epithelial ridge cell cultures from postnatal rat cochlea].

Objective: To investigate the effect of Hath1 (human atonal homolog 1) overexpression on greater epithelial ridge (GER) cells from postnatal rat cochlea in vitro.

Methods: GER cells were isolated by using a combinatorial approach of enzymatic digestion and mechanical separation from P1 rat cochlear. The GER cell cultures were infected by adenovirus containing Hath1 and enhanced green fluorescent protein (ad-Hath1-EGFP), while transfecting EGFP(ad-EGFP) was as controls.

[Relevance between clinical behavior and bionomical findings of acoustic neuromas].

Objective: To evaluate the relationship between labeling index (LI) Ki-67, proliferating cell nuclear antigen (PCNA) and transforming growth factor-beta1 (TGF-beta1) with the clinical behavior of acoustic neuroma.

Methods: Expression of Ki-67, PCNA and TGF-beta1 was detected by immunohistochemistry in 53 specimens of acoustic neuromas. The relationship among tumor proliferation, histological representation, size of tumor, clinical proliferation index of tumor and tumor proliferation activity were analyzed.

[In vitro culture of greater epithelial ridge cells from rat cochleae].

Objective: To establish in vitro culture systems of greater epithelial ridge (GER) cells from rat cochlear and to investigate the characterization, growth pattern and ultrastructure of GER cells.

Methods: Using a combinatorial approach of enzymatic digestion and mechanical separation to allow isolation and culture of GER cells from P1 rat cochleae. The dissociated GER cells were cultured in serum-free or 10% fetal bovine serum DMEM respectively.

Isolation, growth and differentiation of hair cell progenitors from the newborn rat cochlear greater epithelial ridge.

Mammalian cochlear hair cell loss is irreversible and leads to permanent hearing loss. To restore hearing physiologically, it is necessary to generate new functional hair cells either from endogenous cells or from exogenously transplanted hair cells/progenitors. Previous studies suggest that cochlear greater epithelial ridge (GER) and lesser epithelial ridge (LER) cells are capable of differentiating into hair cells.

[Expression of three kinds of transcription factors in greater epithelial ridge cells of rat cochlear].

Objective: To detect the expression of Math1, Hes1 and Hes5 in greater epithelial ridge (GER) cells of rat cochlear and explore their influence on hair cell differentiation.

Methods: Postnatal day 0 (P0), day 1 (P1) , day 3 (P3) day 4 (P4) and day 5 (P5) rat cochlear were dissected respectively and then pure GER cells were separated by a combinatorial approach of attachment and mechanical separation. The total RNA of GER cells was extracted by Trizol one step method and the expression of Math1, Hes1 and Hes5 in GER cells was detected with reverse transcription polymerase chain reaction.

[Effects of noise on antioxidant enzymes of cochlea in guinea pigs].

Objective: To investigate the effect of noise on the antioxidant enzymes of cochleae.

Methods: 16 male pigmented guinea pigs (250 - 300 g) were randomly divided into 2 groups, control group and noise group. Each group had 8 animals.

[Construction of bicistronic eukaryotic vector containing basic fibroblast growth factor and study of their functions in gene therapy for hearing impairment].

Objective: To construct basic fibroblast growth factor(bFGR) and enhance green fluorescence protein(EGFP) fusion gene eukaryotic expression vector internal ribosome entry site (pIRES)-bFGF-GFP and to evaluate the effect of transduction bFGF gene on noise induced hearing-loss in inner ear hair cells of guinea pigs.

Methods: Human bFGF cDNA was inserted into mammalian expressed plasmid pIRES-EGFP. The recombinant expression plasmid pIRES-bFGF-EGFP was transfected into inner ear of guinea pigs, using lipofectin method.