Search

In this study, porous gelatin microspheres (GMSs) were constructed to improve the neuroprotective effect of basic fibroblast growth factor (bFGF) on spinal cord injury. GMSs were prepared by a W/O emulsion template, followed by cross-linking, washing and drying. The particle sizes and surface porosity of the blank GMSs were carefully characterized by scan electronic microscopy. The blank GMSs have a mean particle size of 35μm and theirs surface was coarse and porous. bFGF was easily encapsulated inside the bulk GMSs through diffusion along the porous channel. 200μg of bFGF was completely encapsulated in 100mg of GMSs. The bFGF-loaded GMSs displayed a continuous drug release pattern without an obvious burst release over two weeks in vitro. Moreover, the therapeutic effects of bFGF-loaded GMSs were also evaluated in spinal cord injury rat model. After implantation of bFGF-loaded GMSs, the recovery of the motor function of SCI rats were evaluated by behavioral score and foot print experiment. The motor function of SCI rats treated with bFGF-loaded GMSs was more obvious than that treated with free bFGF solution (P<0.05). At the 28th days after treatment, rats were sacrificed and the injured spinal were removed for histopathological and apoptosis examination. Compared with treatment with free bFGF solution, treatment with bFGF-loaded GMSs resulted in a less necrosis, less infiltration of leukocytes, and a reduced the cavity ratio and less apoptotic cells in injured spinal(P<0.01), indicating its better therapeutic effect. Implantable porous GMSs may be a potential carrier to deliver bFGF for therapy of spinal cord injury.

Tumor necrosis factor alpha (TNFα) is present in cyst fluid and promotes cyst growth in autosomal dominant polycystic kidney disease (ADPKD). However, the cross-talk between TNFα and PKD associated signaling pathways remains elusive. In this study, we found that stimulation of renal epithelial cells with TNFα or RANKL (receptor activator of NF-κB ligand), a member of the TNFα cytokine family, activated either the PI3K pathway, leading to AKT and mTOR mediated the increase of Id2 protein, or MAPK and Cdk2 to induce Id2 nuclear translocation. The effects of TNFα/RANKL on increasing Id2 protein and its nuclear translocation caused significantly decreased mRNA and protein levels of the Cdk inhibitor p21, allowing increased cell proliferation. TNFα levels increase in cystic kidneys in response to macrophage infiltration and thus might contribute to cyst growth and enlargement during the progression of disease. As such, this study elucidates a novel mechanism for TNFα signaling in regulating cystic renal epithelial cell proliferation in ADPKD.

We present for the first time that histone deacetylase 6 (HDAC6) regulates EGFR degradation and trafficking along microtubules in Pkd1 mutant renal epithelial cells. HDAC6, the microtubule-associated α-tubulin deacetylase, demonstrates increased expression and activity in Pkd1 mutant mouse embryonic kidney cells. Targeting HDAC6 with a general HDAC inhibitor, trichostatin (TSA), or a specific HDAC6 inhibitor, tubacin, increased the acetylation of α-tubulin and downregulated the expression of EGFR in Pkd1 mutant renal epithelial cells. HDAC6 was co-localized with EGF induced endocytic EGFR and endosomes, respectively. Inhibition of the activity of HDAC6 accelerated the trafficking of EGFR from early endosomes to late endosomes along the microtubules. Without EGF stimulation EGFR was randomly distributed while after stimulation with EGF for 30 min, EGFR was accumulated around α-tubulin labeled microtubule bundles. These data suggested that the Pkd1 mutation induced upregulation of HDAC6 might act to slow the trafficking of EGFR from early endosomes to late endosomes along the microtubules for degradation through deacetylating α-tubulin. In addition, inhibition of HDAC activity decreased the phosphorylation of ERK1/2, the downstream target of EGFR axis, and normalized EGFR localization from apical to basolateral in Pkd1 knockout mouse kidneys. Thus, targeting HDAC6 to downregulate EGFR activity may provide a potential therapeutic approach to treat polycystic kidney disease.