Clone screening and interference efficiency of seed cells with CCL20 gene knockdown for tissue-engineered skin / 中华外科杂志

<p><b>OBJECTIVE</b>To screen stable cell clones of CCL20 gene knockdown and assess their interference effects, recombinant lentivirus vectors with CCL20 gene specific shRNA were applied to infect human immortal keratinocyte line (HaCaT).</p><p><b>METHODS</b>The three pHSER-CCL20-shRNA-GFP vectors (pHCG-1 and pHCG-2 were CCL20 gene specific, and pHCG-3 was used as mismatch control) have been previously constructed. The virus packaging cell line 293FT was transfected with these vectors by using CaCl2 methods to produce lentiviral particles. After the viral titers of these three harvested cell supernatants were determined by flow cytometry, HaCaT cells were transfected by these viruses and screened under the pressure of G418. The CCL20 mRNA from HaCaT cell clones and the CCL20 protein levels in the supernatants of HaCaT cell clones were detected by Real-time RT-PCR and ELISA, respectively.</p><p><b>RESULTS</b>The titers of three lentiviruses were 7.08 x 10(5) transduced units (TU)/ml, 1.88 x 10(5) TU /ml and 2.08 x 10(5) TU/ml, respectively. Two HaCaT cell clones from each lentiviral vectors were obtained after G418 screening for 5 - 8 weeks. Four CCL20 gene specific clones showed stable interference effect in both Real-time RT-PCR and ELISA. The mRNA expression and protein level of CCL20 gene specific clones were down regulated significantly.</p><p><b>CONCLUSIONS</b>The four human immortal keratinocyte clones with long term CCL20 gene knockdown have been screened by recombinant lentivirus vectors with CCL20 gene specific shRNA. These clones might be served as seed cells for novel tissue-engineered skin with lower rejection.</p>

Study on influencing factors in efficiency of introducing gene into human keratinocyte (KC) / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the effect of plasmids in different size and gene transfection protocol on efficiency of introducing gene into human KC.</p><p><b>METHODS</b>Four plasmids in different size, inclu-ding pSUPER-enhanced green fluorescent protein (EGFP), pEGFP-N2, pHSER-green fluorescent protein (GFP) and ploxP-EGFP, were transfected into immortal human KC line (HaCaT) and human embryo kid-ney cell line (293FT) separately following transfection protocols of liposome (LTP), cation polymerizer (CPTP), electroporation combined with nucleus transfection agent (ETP) and lentivirus. 293FT was used as control. GFP expression was observed under inverted fluorescence microscope. The transfection efficiency (TE) was calculated.</p><p><b>RESULTS</b>(1) The four plasmids could be introduced into HaCaT (TE, 1.0%-3.3%) and 293FT (TE, 80.0%-84.7% ) following LTP. (2) The four plasmids could also be introduced into HaCaT (TE, 1.0%-3.7% ) and 293FT (TE, 81.3%-86.7% ) following CPTP. (3) Two shorter plasmids (pSUPER-EGFP and pEGFP-N2) could be introduced into HaCaT by ETP with higher TE than the othr two longer plasmids (pHSER-GFP and ploxP-EGFP), which were 22.3% and 19.0% vs. 4.0% and 3.3%, respectively. (4) pHSER-GFP packaged by lentivirus could be introduced into HaCaT with the TE reaching 97.0%, which surpassed the above three protocols.</p><p><b>CONCLUSIONS</b>It is difficult to introduce exogenous gene into human KC by LTP or CPTP; TE of lentivirus transfection protocol apparently surpasses</p>

Ectopic expression of keratin 19 and integrin beta1 during wound healing process after microskin grafting in rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the characteristics of keratin 19 and integrin beta1 expressions in the wound after microskin grafting , and to investigate the healing mechanism.</p><p><b>METHODS</b>Full layer skin defects were created in twenty Sprague-Dawley rats and they were divided into two groups, i.e., A group (with grafting of autologous microskin accounting 10% in weight of epidermis loss from skin defect), B group (with grafting of autologous microskin and allogeneic microskin, accounting 10% and 40% weight of epidermis loss respectively in skin defect). The wound healing rate and contraction rate were observed at 2,3,4 post-grafting week (PGW), and the expression and distribution of keratin 19 and integrin beta1 were observed at 2 and 4 PGW.</p><p><b>RESULTS</b>The wound healing rate in the B group on 2 and 3 PGW was obviously higher than that in A group [(85 +/- 5)% vs. (53 +/- 10)%, (84 +/- 8)% vs. (65 +/- 9)%, P < 0.01]. No obvious difference in wound contraction rate between the two groups was observed on the 2, 3 and 4 PGW (P > 0.05). Cells with expression of keratin 19 and integrin beta1 were observed in the suprabasal layers of the epidermis in healing wound, but not in the basal membrane. Integrin beta1 positive expression cells were not observed in the suprabasal layers until 4 PGW.</p><p><b>CONCLUSION</b>Mixed grafting with autogenous and allogenous microskin can improve wound healing. Ectopic expression of keratin 19 and integrin beta1 exists during wound healing process after microskin grafting.</p>

Study on the optimal ratio of autoskin and alloskin during mixed microskin grafting / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of different amount of allogeneic microskin in mixed grafting with certain quantity of autologous microskin on wound healing in rats. Methods Male Wistar rats served as alloskin donor rats. Forty female SD rats with full thickness skin defect were enrolled in the study, and they were randomly divided into four groups, i.e. group I (n=10, with allogeneic microskin graft at area expansion rate of 10:3); group II (n=10, with autologous microskin graft at area expansion rate of 10:1); group III (n=10, with mixed grafting of autologous and allogeneic microskin at area expansion rate of 10:1, respectively); group IV (n=10, with mixed grafting of autologous and allogeneic microskin at area expansion rate of 10:1 and 10:3, respectively). The wound healing rate, wound contraction rate and histological changes were observed at the 2, 3 and 4 post graft weeks (PGW).</p><p><b>RESULTS</b>(1) In group I, there was mainly granulation tissue with some de novo epithelial cells appearing at the wound edge along with the rejection of grafted allogenous skin in the rat wound. In group II, there was still some granulation tissue remaining at 2 PGW due to insufficient amount of microskin. However, the wounds in the mixed grafting group appeared almost totally epithelialized. (2) Various amounts of mononuclear inflammatory cell infiltration and different degrees of angiectasis were observed in the dermal layer after the skin grafting in all groups, especially in group II and IV. There was thickening of the epithelial layer in all groups except group I. (3) The wound healing rate decreased obviously along with the development of rejection in group I at 2 to 4 PGWs. The wound healing rate was (55 +/- 26)% in group II, which was obviously lower than that in group III (88 +/- 6)% and in group IV (76 +/- 10)% at 3 PGWs (P < 0.01). (4) The contraction rate of the wound in group IV (69 +/- 7)% was much higher than that in group I (58 +/- 11)% at 3 PGWs (P < 0.05), and there was no difference among all the other groups.</p><p><b>CONCLUSION</b>Wound healing can be obviously accelerated by mixing some autologous microskin with appropriate amount of alloskin. Moreover, certain amount of autologous microskin (expansion rate 10:1) mixed with the same proportion of allogeneic microskin seems to be more beneficial in promoting wound healing.</p>

Prolongation of the survival of skin allografts by intravenous injection of neuraminidase-treated donor bone marrow cells in rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To optimize the best concentration of neuraminidase (Neu) that enhances the migration of neuraminidase (Neu)-treated donor bone marrow cells (dBMCs) to the liver, and observe the influence of short-term cyclosporin A(CsA) application combined with intravenous injection (i.v.) of Ne treated dBMCs on the survival of skin allografts.</p><p><b>METHODS</b>The experiment consisted of two parts. For selection of an appropriate concentration of Neu, 26 female Wistar rats were randomly divided into four groups. The dBMCs were prepared by routine method and treated with four concentrations (0, 0.5, 1.0, 2.0 U/ml) of Neu at 37 degrees C for 30 min. The untreated and Neu-treated dBMCs were labeled by 99mTc, and injected via the tail veins to female Wistar rats in each group, respectively. After five hours, the radioactivity of various organs collected from sacrificed rats was measured by a gamma counter, and the values were expressed as percentage of total radioactivity of all organs from the same rat. To observe the survival of skin allograft, 23 male Wistar rats were randomly divided into control group, untreated dBMCs group and Neu-treated dBMCs group. All rats in each group were grafted with skin allografts from male Sprague-Dawley (SD) rats. The dBMCs from the same donor without and with Neu treatment by the concentration selected from the above experiment were injected via the tail veins of female Wistar rats in untreated dBMCs group and Neu-treated dBMCs group, respectively. Rats in untreated dBMCs group and Neu-treated dBMCs group received CsA (10 mg/kg) through intraperitoneal injection (i.p.) at 2 and 5 days post-grafting. Neither dBMCs or CsA were given in the control group. The survival of allograft skin in each group was checked and photographed daily after 5 days post operation.</p><p><b>RESULTS</b>When the concentration of Neu was 1.0 U/ml, the percentage of dBMCs in liver was (75.3 +/- 9.8) %, which was obviously higher than that in 0 U/ml group [(58.9 +/- 4.2%)], (P < 0.01), indicating that the optimal concentration of Neu was 1.0 U/ml. The survival time of skin allografts in rats of Neu-treated dBMCs group was prolonged significantly in comparison with that of the rats in dBMCs group without Neu treatment (P < 0.01). The survival time in both dBMCs group and Neu-treated dBMCs group was longer that of control group (P < 0.01), and it was prolonged in Neu-treated dBMCs group compared with that in dBMC group.</p><p><b>CONCLUSION</b>Administration of proper concentration of Neu can increase the affinity of dBMCs to the liver, and promote the Neu-treated dBMCs to migrate to liver. The intravenous injection of Neu-treated dBMCs combined with short-term CsA administration can delay the rejection of skin allografts in rats.</p>

Influence of mixed grafting of autologous and allogeneic microskin on burn wound healing in rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the influence of mixed grafting of autologous and allogeneic microskin on burn wound healing.</p><p><b>METHODS</b>Autologous microskin grafting (expansion rate 5:1) was employed as control. Autologous microskin mixed with the allogeneic microskin with the thickness of 0.3 mm and 0.6 mm, respectively, were designated as experimental groups 1 and 2 (EP1 and EP2). The wound healing rate, wound contraction rate, and histological changes were observed on the 2nd, 3rd and 4th weeks after the grafting.</p><p><b>RESULTS</b>The wound healing rate in two experimental groups (94.58 +/- 3.99)% in EP1, and (95.28 +/- 1.93)% in EP2 was significantly higher than that in the control group (88.28 +/- 6.85)% at the end of the 2nd week after the grafting (P < 0.05) The wound healing rate in experimental group 2 (94.55 +/- 3.47)% was obviously higher than that in control (88.51 +/- 5.59)% and experimental group 1 (89.51 +/- 4.70)% at the end of the 3rd week after grafting (P < 0.05). There was no obvious difference in wound healing rate among the three groups at the end of the 4th week after grafting. Obvious lymphocytic infiltration was observed by histological examination between epidermis and dermis in the two experimental groups at the end of the 2nd week after grafting. But there was no obvious difference among the three groups 4 weeks after grafting.</p><p><b>CONCLUSION</b>The wound healing could be improved by mixed skin grafting with appropriate quantity of allogeneic and autologous microskin. Furthermore, the wound contraction could be ameliorated if the thickness of allogeneic dermis was increased in the mixed grafting even with the same proportion of allogeneic to autologous microskin.</p>