Primary study on the differentiation mechanism of embryonic stem cells to epidermal like cells induced by human amnion

AIM: To investigate the mechanism by which human amnion induced mouse embryonic stem (ES) cells to differentiate into epidermal like cells. METHODS: ES- BALB/ c cells were cocultured with human amnionintranswells for 4 - 5 days , andthose cultured alone without amnion were taken as control group. The morphological differentiation were observed . The committed differentiation of EScells into epidermal like cells were detected by integrin-β₁ , CK19 , CK15 andinvolucrin immunohistochemistry , respectively .RESULTS: After 4-5 days of coculture, ES cells differentiated into single layer of epidermal like cells, fitted tightly, with polyhedral in shape. The immunohistochemical staining results showed that, most of the cells were integin-β₁ positive, only a few cells were CK19 and CK15 positively stained. Most of the cells in control group died, the survived ones were different in morphological shapes, and no integrin-β₁, CK19 and CK15 positive cells were found. CONCLUSION: Soluble substances secreted by human amnion may play an important role in inducing the differentiation of mouse ES cells into epidermal like cells.     

Comparison of different conditions inducing embryonic stem cells

AIM: To evaluate the different conditions inducing mouse embryonic stem cells (ESC) in vitro to differentiate into cardiomyocytes. METHODS: BRL conditioned medium was used to promote the growth of ESC and maintain them in an undifferentiated state. During the inducing process, retinoic acid (RA), DMSO, activin-A and TGF-β₁ were used as inducing reagents, and made up six kinds of differentiating medium. Then a three-step method inducing ESC cultured in hanging drops, in suspension and in plating was used to induce the differentiation of ESC. RESULTS: ESC were induced in vitro to differentiate into cardiomyocytes. Of all groups, the highest differentiating rate was observed in the group induced by activin-A (20 μg/L) and TGF-β₁ (2 μg/L). CONCLUSION: The inducing conditions including activin-A (20 μg/L) and TGF-β₁ (2 μg/L) is very valuable in inducing ESC differentiation into cardiomyocytes.     

Effect of streptomycin on electrophysiological changes caused by rising of left ventricular afterload in rabbits

AIM: The aim of this study was to study the changes of rabbit heart electrophysiological properties caused by increasing left ventricular afterload, and to assess the effects of streptomycin or verapamil on these changes. METHODS: The rabbit heart preparation in situ was used, and the afterload of left ventricle was increased by clipping in part the root of ascending aorta. The changes of heart electrophysiological parameters including relative refractory period (RRP), effective refractory period (ERP), monophasic action potential duration (MAPD₉₀) and ventricular fibrillation threshold(VFT) were observed before and after altering the afterload of left ventricle and were compared in the absence and presence of streptomycin or verapamil. RESULTS: The rising of left ventricular afterload led to shortening of RRP, ERP and MAPD₉₀, and to descent of VFT (P＜0.01). Streptomycin inhibited these changes of heart electrophysiological parameters caused by elevation of left ventricular afterload. In contrast, verapamil had no effects on the afterload-related changes of RRP, ERP and MAPD₉₀ (P＞0.05) except increasing of VFT (P＜0.01). CONCLUSION: The electrophysilogical effect of streptomycin appears consistent with inhibition of stretch-activated ion channels, suggesting that the stretch-activated ion channels might be involved in the afterload-related changes of heart electrophysiological properties.     

IgA1 from patients with IgA nephropathy induced release of calcium,up-regulation of TGF-β mRNA expression and secretion of fibronectin in human glomerular mesangial cells

AIM: To study and compare the pathophysiological effects of serum IgA₁ from both the patients with IgA nephropathy (IgAN) and healthy controls on human mesangial cells (HMC). METHODS: Serum IgA₁ was isolated with Jacalin affinity chromatography and heated to form aggregates (aIgA₁). Primary HMC were cultured and passage 3 and passage 4 of the cells were used. Intracellular calcium release was assayed with confocal analysis. Expression of TGF-β mRNA and the content of supernatant fibronectin were tested by RT-PCR and indirect competitive ELISA, respectively. RESULTS: aIgA₁ from patients with IgAN was shown to induce release of intracellular calcium, up-regulation of expression of TGF-β mRNA and secretion of fibronectin in HMC in a similar time-dependent manner as aIgA₁ from healthy controls, but the effects of the former were much stronger and the durations was much longer (P<0.05, respectively). CONCLUSION: IgA₁ from patients with IgAN was shown to be able to stimulate HMC with a stronger biological effects than that from healthy controls. It is suggested that direct interaction between IgA₁ from patients with IgAN and HMC may be another mechanism in the pathogenesis of IgAN.     

Characteristics of transient outward potassium current in repolarization 1 phase from the canine right ventricular mid-myocardial cells

AIM: To examine the electrophysiological characteristics of transient outward potassium current(Ito₁) in repolarization 1 phase from the canine right ventricular M cells. METHODS: By use of whole cell patch-clamp technique, we quantitatively researched the ionic intensity, density of Ito₁ and the notch magnitude of action potential in repolarization 1 phase. RESULTS: (1) The activating process of Ito₁ of canine right ventricular M cells presented evident voltage-dependency. Under the condition of 37℃, 5 000 ms, 0 mV and +70 mV, the average peak Ito₁ intensity of right ventricular M cell were (690±380) pA and (3 130±1 910) pA, respectively (P＜0.01). (2) The Ito₁ intensity of canine right ventricular M cell possessed obvious frequent dependency. Under the condition of 37℃,+70 mV, 500 ms and 5 000 ms, the average peak Ito₁ intensity were (1 690±830) pA,(3 130±1 910) pA, respectively(P＜0.01), corresponding to the increase of action potential "spike-dome" magnitude in repolarization 1 phase. CONCLUSION: Potent Ito₁ as well as the "spike-dome"-like action potential figure mediated by Ito₁ is one of the prominent electrophysiological characteristics of the canine right ventricular M cells.     

Effect of CoQ10 on apoptosis and proliferation of cultured mouse microvascular endothelial cells and it's mechanism

AIM: To study the inhibitory effect of CoQ₁₀ on the apoptosis of microvascular endothelial cells and it's probable mechanism. METHODS: Using serum pharmacology method and cytoflowmetery, the effects of CoQ₁₀ at different concentrations on apoptosis and proliferation in cultured mouse brain microvascular endothelial cells (bEnd.3) were investigated. The expression of Fas protein and Bcl-2 protein were observed with immunocytochemical method (ABC). RESULTS: The cell apoptosis was inhibited significantly in CoQ₁₀ groups (50 μL and 25 μL) in cultured bEnd.3 cells. The results of immunocytochemical staining showed that the expressions of Fas protein was inhibited and Bcl-2 protein was stimulated significantly in CoQ10 group with above concentration. But there was no significant change in cell proliferation. CONCLUSIONS: CoQ₁₀ may inhibit apoptosis of microvascular endothelial cells (bEnd.3) via up-regulation of Bcl-2 and down-regulation of Fas. Authors suggest that this is one of the protection mechanisms of CoQ₁₀ from dysfunction of microvascular endothelial cells.     

Effects of different HA/ZrO2 composites on adherence,proliferation and osteogenesis of cultured MSCs

AIM: To study the adherence, proliferation and osteogenesis effects of different composites on cultured mesenchymal stem cells (MSCs). METHODS: Zirconium oxide (ZrO₂) with monolayer hydroxyapatite (HA) composite and ZrO₂ with gradient HA composite were prepared using dry-laying method. The surface topography of the composites was observed. The rabbit MSCs were isolated and cultured on HA/ZrO₂ monolayer composite, HA/ZrO₂ gradient composite, pure HA or pure ZrO₂ slices. The adherence, proliferation and osteogenesis of the MSCs were assayed. The activity of alkaline phosphatase was detected. The mRNA expression of collagen I, osteocalcin and osteopontin was determined by RT-PCR. RESULTS: The discontinuous or continuous HA surface was observed in HA/ZrO₂ monolayer composite,while the surface of prepared HA/ZrO₂ gradient composite was fairly rough with porosity. The X-ray diffraction analysis shows that after megatemperature sintering, the ZrO₂ phase on the surface of the composite still remained, while the HA phase transformed to β-Ca₃(PO₄)₂(β-TCP), α-Ca₃(PO₄)₂(α-TCP) and CaZrO₃ phases. Cell culture showed that the HA/ZrO₂ gradient composite was in favour of cell adherence. The alkaline phosphatase activity in MSCs on pure HA slice was significantly increased compared compared with other groups.The mRNA expression of collagen I, osteocalcin and osteopontin in MSCs on HA/ZrO₂ composites and pure HA silice was higher than that in control group,especially the expression of collagen I. CONCLUSION: The HA/ZrO₂ garded composite promotes the proliferation of MSCs to a certain extent, and also promotes the osteogenesis differentiation of MSCs.     

Preliminary separation and identification of quiescent and activated neural stem cells in mouse embryonic cerebral cortex

AIM To isolate and identify quiescent and activated neural stem cells from mouse embryonic cerebral cortex. METHODS Two cell clusters derived from mouse cerebral cortex on embryonic day 14.5 were separated by flow cytometry. The expression of stem cell marker Pax6 and proliferation marker Ki67 was examined by immunofluorescence. The mRNA expression of stem cell marker genes Pax6, Oct4, Sox2 and Nanog were detected by RT-qPCR. Cell cycle was analyzed by flow cytometry and RT-qPCR. Proliferation ability was investigated by in vitro cell culture. RESULTS In both 2 groups, the cells expressed Pax6. Immunofluorescence staining of Ki67 in the big cell group was positive, while that in small cell group was negative. Cell cycle assay showed that the proportion of G₀/G₁ phase in the small cells was higher than that in the big cells, the G₂/M phase proportion was 0, and the expression of cyclin A and cyclin B was lower than that in the big cells (P<0.05). When cultured in vitro, the number of microspheres formed by the small cells was smaller and the formation speed was slower than those of the big cells. After digestion of microspheres, Pax6 and Ki67 staining of both big and small cells was positive, and the positive rates were not different (P>0.05), indicating that the quiescent neural stem cells were activated. CONCLUSION The 2 cell clusters are quiescent and activated state of neural stem cells. The activated stem cells have strong abilities of self-renewing and proliferation, while these abilities of quiescent stem cells are poor. The quiescent stem cells can translate into activated ones when cultured in vitro for a period.     

Preliminary study of genotoxicity of HA/ZrO2 composite particles in vitro

AIM: To evaluate the genotoxicity of the hydroxyapatite/ZrO₂(HA/ZrO₂) composite particles by using the in vitro micronucleus test (MNT). METHODS: The HA/ZrO₂ composite particles prepared by sintering at high temperature and pressure using the powder of HA and ZrO₂ with different proportions were compared with the pure HA particle and pure ZrO₂ particle. The suspension of the composite particles was made. The rabbit mesenchymal stem cells were isolated and cultured. The promotive effect of the composite particles on the proliferation of the rabbit mesenchymal stem cells was detected by MTT method. The genotoxicity of the composite particles to the rabbit mesenchymal stem cells was measured by MNT method. RESULTS: The MTT test showed that both of the pure HA particle and the composite particles containing HA promoted the proliferation of rabbit mesenchymal stem cells. However, no promotive effect of the pure ZrO₂ particle on the proliferation of rabbit mesenchymal stem cells was observed. The MNT test showed no significant difference between HA group and negative control group (P>0.05), and significant difference between HA group and positive control group (P<0.05). The difference between ZrO₂ group and negative control group was significant (P<0.01), and the difference between ZrO₂ group and positive control group was insignificant (P>0.05). CONCLUSION: The increase in genotoxicity of HA/ZrO₂ composite particle is dependent on the proportion of ZrO₂ and the concentration of the composite. The 30%wt HA/70%wt ZrO₂ composite at the concentration of 200 mg/L shows significant genotoxicity.     

Inhibitory effect of ATP on proliferative signaling in immortalized human fibroblasts

AIM: To investigate the inhibitory effects of ATP on proliferation signaling in immortalized human fibroblasts. METHODS: Immortalized human fibroblasts were treated with ATP, ATP conbined with calcium or potassium channel antagonists, respectively. The intracelluar-free calcium ([Ca²⁺]i), inositol 1,4,5-trisphosphate(IP₃) levels and cell viability were detected at different time points. RESULTS: ATP significantly increased the [Ca²⁺]i and decreased the IP₃ level in immortalized human fibroblasts, especially at initial stage (P＜0.01) . Compared to ATP alone, the proliferation rates remarkably increased when calcium or potassium channel antagonists were used (P＜0.01, respectively) with ATP. CONCLUSION: The calcium and potassium channels and IP₃ involved in the inhibitory effects of ATP on the proliferative signaling in immortalized human fibroblasts.     

The alteration of extracellular sodium and potassium ionic activities of hippocampal neurons in epileptiform rats kindled by coriaria lactone

AIM and METHODS: The sodium ion Na⁺ and potassium ion K⁺ selective microelectrodes were used to measure changes of ionic activity of extracellular sodium and potassium( [Na⁺]_o, [K⁺]_o) in hippocampus and hippocampal slice during epieptic seizure induced by intrahippocampal microinjection of coriaria lactone(CL) in rats and perfusing hippocampal slice with CL. RESULTS:30 s, 1min and 2min after injection of CL into hippocampus, the [Na⁺]_o decreased 27.7 mmol/L, 50.3 mmol/L, 57.8 mmol/L respectively and the [K⁺]_o increased 2.3 mmol/L, 2.4 mmol/L, 2.9 mmol/L respectively compared with control values(P＜0.01). The [K⁺]_o returned to the control level 3min after local application of CL, but the[Na⁺] _o was still lower than that of control group(P＜0.01). The [Na⁺]_o and the [K⁺]_o were measured also in hippocampal silces and results are similar to those of experiments in vivo. CONCLUSION: The influx of Na⁺and the flux of K⁺occurred during epileptiform discharges of hippocampal neurons induced by administration of CL.     

Effects of Aβ1-42-induced microglial cells on survival of neural stem cells in vitro

AIM: To explore the effects of β-amyloid protein 1-42 (Aβ_1-42)-induced microglia on the survival of cultured neural stem cells (NSCs) in vitro . METHODS: Using the Transwell chambers to build a coculture system of NSCs and microglia, we detected the proliferation, differentiation and apoptosis of the NSCs with the microglia before and after induction by Aβ_1-42. RESULTS: Compared with non-intervention group, the proliferation rate of NSCs in Aβ_1-42 intervention coculture group decreased, as well as the positive expression rates of microtubule-associated protein 2 (MAP-2) and choline acetyltransferase. CONCLUSION: The inflammation mediated by Aβ_1-42 inhib their the proliferation of NSCs and induces their apoptosis. Inflammation also significantly reduces the ratio of NSCs differentiating to neurons, especially to cholinergic neurons.     

Calcium overload and reactive oxygen species mediate high glucose-induced apoptosis of mouse osteoblast MC3T3-E1 cells

AIM: To investigate the role of reactive oxygen species (ROS) and calcium overload in the apoptosis of MC3T3-E1 cells induced by high glucose. METHODS: Cultured mouse skull bone-derived osteoblast cell line MC3T3-E1 was treated with high concentration of D-glucose to induce apoptosis. The proliferation of MC3T3-E1 cells was detected by MTT assay after treated with different concentrations of D-glucose for 24 h and 48 h. The apoptotic rate and the intracellular levels of calcium and ROS were also measured after the cells were treated with high glucose (35 mmol/L) for 24 h. RESULTS: After high glucose treatment, the cell proliferation was inhibited. The early apoptosis and total cell death increased to (24.16?3.53)% and (63.74?4.32)%,respectively. High glucose treatment significantly increased intracellular levels of ROS and Ca²⁺. The increased apoptotic rate was reduced by addition of antioxidant N-acetylcysteine and calcium chelator BAPTA-AM. Inhibition of store-operated Ca²⁺ channels by La³⁺ also decreased the intracellular level of Ca²⁺ and cell apoptosis induced by high glucose. CONCLUSION: High glucose increases intracellular ROS level and the release of Ca²⁺ through the store-operated Ca²⁺ channels, thus resulting in intracellular Ca²⁺ overload and leading to apoptosis of osteoblasts.     

Effect of ginsenoside Rh2 on cultured PC-3M cells in vitro

AIM:To explore the influence of ginsenoside Rh₂ on cultured PC-3M cell cycle in vitro. METHODS:DNA content was measured using [³H]-TdR incorporation assay. To analysis the cycle changes of PC-3M cells, flow cytometry was used in the experiment.RESULTS:The results indicated that the rate of [³H]-TdR incorporation was lower in Rh₂-treated cells than the control in a dose-dependent manner. Flow cytometry demonstrated that the pecent of G₁ phase treated with Rh₂ was higher than that of control. CONCLUSION:These results suggested that PC-3M cells cultured with Rh₂ for 24 h were blocked at G₁ phase, and Rh₂ inhibited the growth of PC-3M cells in vitro.     

Effects of simulated ischemia/reperfusion on spontaneous action potentials in primary cultured sinoatrial node cells and the influence of pinacidil

AIM: To study the effects of ischemia/reperfusion (I/R) on primary cultured sinoatrial node (SAN) cells and the influence of pinacidil (a K_ATP channel activator). METHODS: The SAN cells were isolated from newborn rats and purified. The 48 h cultured cells were cultivated in following mediums: simulated reperfusion solution as normal control, simulated ischemia/reperfusion solution (I/R), Pinacidil+I/R (P+I/R), 5-HD+P+I/R and 5-HD+I/R. Spontaneous action potentials were recorded by ruptured-patch whole-cell technique in current clamp (I=0) and the maximum diastolic potential (MDP), upstroke velocity (UV), action potential overshoot (APO), interbeat interval (IBI) and action potential durations at 50% repolarization (APD₅₀) were measured. RESULTS: Compared with control group, simulated ischemia/reperfusion shorten APD₅₀, reduced UV, MDP and APO. Exposed to pinacidil, MDP of cells in I/R groups was hyperpolarized; IBI, UV and APO were increased; APD₅₀ was shorten. 5-HD couldn't block the effects of pinacdil on APD₅₀, IBI and MDP, but reversed its actions on increasing UV and APO. CONCLUSIONS: Pinacidil made changes of AP in I/R group by opening different K_ATP channels of SAN cells. The role of this changes on protection in SAN cells during ischemia/reperfusion requires further investigation.     

Electrophysiological characteristics of the membrane current of cardiomyocytes-like cells derived from rat bone marrow mesenchymal stem cells

AIM: To study the electrophysiological characteristics of the membrane currents of cardiomyocytes-like cells derived from rat bone marrow mesenchymal stem cells (MSCs).METHODS: MSCs were induced,cultured and identified according to the reference.At the fourth week after treatment with 5-azacytidine(5-aza),cardiomyocytes-like cells were detected for the membrane current with the whole-cell patch-clamp technique and compared with the undifferentiated MSCs.RESULTS: The undifferentiated MSCs only expressed potassium currents.MSCs were stained positive for troponin T after treatment with 5-aza,and two kinds of inward currents and three kinds of outward currents were expressed.They respectively were the fast inward sodium current (I_Na),the L-type calcium current (I_Ca),the transient outward potassium current (I_to),the ultra-rapid delayed rectifier potassium current (I_kur) and the slow delayed rectifier potassium current (I_ks).Compared with the undifferentiated MSCs,the potassium currents of cardiomyocytes-like cells derived from MSCs were mainly made up of I_kur and I_ks.CONCLUSION: After treatment with 5-azacytidine,MSCs are differentiated into cardiomyocytes-like cells,which express the current of I_Na,I_Ca,I_to,I_kur and I_ks.     

Effect of glucagon-like peptide-1(7-36)NH2 on insulin secretion and membrane potentials of pancreatic islet β-cells

AIM: To observe pathomorphological changes in cerebral cortex and hippocampus in the mouse with synthetic vascular dementia. METHODS: The synthetic vascular dementia model was produced in the mouse. Animals were killed 7 d, 15 d, and 30 d after the operation, brain tissues were removed and embedded in paraffin. Section of 8μm thickness were stained with hematoxylin-eosin(HE) and Nissl methods, and observed with light microscope. RESULTS: The cerebral cortex in the mouse became thinner on the seventh day, karyopyknosis in partial nervous cells was formed, the number of local neurons was reduced, sieve structure was observed, and glial cells proliferated, with the similar results 15 d and 30 d after operation. Model mouses hippocampal cells in CA₁ area were reduced and almost disappeared 30 d after operation. At the same time, glial cells were abundantly proliferated, tubercles were formed. Cells in CA₂, CA₃ area were also reduced and hippocampal sclerosis occurred. CONCLUSION: Delayed necrosis of hippocampal pyramidal cells may be the pathological basis of ischemia cerebral vascular dementia.     

Effect of sodium selenite on proliferation of endometrial cancer cells

AIM: To investigate the effect and mechanism of sodium selenite (Na₂SeO₃) on the proliferation of endometrial cancer cells. METHODS: Endometrial cancer Ishikawa cells and HEC-1A cells were treated with Na₂SeO₃. The effect of Na₂SeO₃ on cell proliferation was determined by MTT assay. The effects of Na₂SeO₃ on cell cycle distribution and apoptosis were tested by flow cytometric analysis. The expression of cyclin A was detected by Western blotting. RESULTS: Na₂SeO₃ inhibited the proliferation of Ishikawa cells and HEC-1A cells. For Ishikawa cells, IC₅₀ was 3.26 μmol/L, and for HEC-1A cells, IC₅₀ was 4.77 μmol/L. After treated with Na₂SeO₃, the cells in G₀/G₁ phase were reduced and the cells in S phase and G₂/M phase were increased. Na₂SeO₃ also increased the percentage of apoptosis cells. The result of Western blotting showed that the expression of cyclin A was increased. CONCLUSION: Na₂SeO₃ inhibits the proliferation of endometrial cancer Ishikawa cells and HEC-1A cells via up-regulating the expression of cyclin A, arresting cell cycle and inducing apoptosis.     

Dexamethason enhanced aorta-derived CD105+ mesenchymal stem cells to differentiate into adipocytes

AIM: To investigate whether aorta-derived CD₁₀₅⁺ cells show characteristics of mesenchymal stem cells, and if dexamethason enhances this kind of CD₁₀₅⁺ cells to differentiate into adipocytes. METHODS: The distribution of CD105 in aorta was assessed by imunohistochemistry. The aorta wall cells were isolated and immunophenotypes were identified by FACS. CD₁₀₅⁺ cells were sorted using MACS CD105 micromagnetic beads. The differentiation of CD₁₀₅⁺ cells into adipocytes and osteoblasts was induced under different conditions and indicated by staining of Oil red O, detecting of alkaline phosphatase activity, calcium accumulation stained with silver nitrate and transmission electron microscope analysis, respectively. RESULTS: The endothelial cells, a part of medial smooth muscle cells and adventital fibrblasts were CD105 positive. The isolated aortic arch cells were positive for CD105, CD106, CD44, CD29, and negative for CD45, CD11a, CD11b and HLADR. The CD₁₀₅⁺ cells differentiated into adipocytes contained Oil-Red-O-positive lipid droplets, the osteocytes with calcium deposition and alkaline phosphatase activity. Ultrastructurally, it was observed that some needle-shaped crystal calcium deposition similar to bone spicules was inside the cytoplasm of induced osteocytes. When the dexamethason was absent in the adipogenic medium, there were no adipocytes with lipid droplets. CONCLUSION: The results demonstrated that CD₁₀₅⁺ cells showed characters of MSCs reside in aortic wall, and was able to differentiate into adipocytes and osteocytes in vitro. Dexamethason enhanced aorta-derived CD₁₀₅⁺ with characters of MSCs to differentiate into adipocytes. These suggested that MSCs might be related with atherosclerosis.     

Protective effect of sodium selenite on human keratinocytes from ultraviolet-B irradiation

AIM: To investigate the protective effect of sodium selenite (Na₂SeO₃) on human keratinocytes under ultraviolet-B (UVB) irradiation. METHODS: The cultured HaCaT cells were divided into 4 groups: (1) normal control group; (2) Na₂SeO₃ group: pretreated with Na₂SeO₃ at doses of 10 nmol/L, 50 nmol/L, 100 nmol/L, 200 nmol/L and 1 μmol/L for 24 h; (3) UVB group: irradiated with UVB at doses of 300, 600 and 900 J/m² ; (4) Na₂SeO₃+UVB group: after pretreated with Na₂SeO₃ for 24 h, irradiated with UVB at doses of 300, 600 and 900 J/m² . The cell proliferation was detected by MTT assay. The apoptotic rates of HaCaT cells treated with UVB at dose of 300 J/m² were assessed by flow cytometry. RESULTS: Compared with normal control group, the cell proliferation activity in UVB group decreased significantly (P<0.05). The cell activity was inversely correlated with the irradiation intensity. No significant difference of the cell activity between Na₂SeO₃ group and normal control group was observed. The cell proliferation in Na₂SeO₃+UVB group was higher than that in UVB group significantly (P<0.05). Na₂SeO₃ at concentration of 100 nmol/L showed the strongest activity to promote cell proliferation. After 300 J/m² UVB irradiation, the apoptotic rate in Na₂SeO₃+UVB group decreased significantly (P<0.05) compared with UVB group. The inhibitory effect of Na₂SeO₃ at concentration of 100 nmol/L on apoptosis was the strongest.CONCLUSION: The damage of human keratinocytes by UVB irradiation is in a dose-dependent manner. The photoprotection performance of Na₂SeO₃ reduces the damage of human keratinocytes induced by UVB irradiation.