Determination of optical properties of normal and adenomatous human colon tissues in vitro using integrating sphere techniques

AIM: The purpose of the present study is to compare the optical properties of normal human colon mucosa/submucosa and muscle layer/chorion, and adenomatous human colon mucosa/submucosa and muscle layer/chorion in vitro at 476.5, 488, 496.5, 514.5 and 532 nm. We believe these differences in optical properties should help differential diagnosis of human colon tissues by using optical methods.METHODS: In vitro optical properties were investigated for four kinds of tissues: normal human colon mucosa/submucosa and muscle layer/chorion, and adenomatous human colon mucosa/submucosa and muscle layer/chorion. Tissue samples were taken from 13 human colons (13 adenomatous, 13 normal). From the normal human colons a total of 26 tissue samples, with a mean thickness of 0.40 mm, were used (13 from mucosa/submucosa and 13 from muscle layer/chorion), and from the adenomatous human bladders a total of 26 tissue samples, with a mean thickness of 0.40 mm, were used (13 from mucosa/submucosa and 13 from muscle layer/chorion). The measurements were performed using a double-integratingsphere setup and the optical properties were assessed from these measurements using the adding-doubling method that was considered reliable.RESULTS: The results of measurement showed that there were significant differences in the absorption coefficients and scattering coefficients between normal and adenomatous human colon mucosa/submucosa at the same wavelength,and there were also significant differences in the two optical parameters between both colon muscle layer/chorion at the same wavelength. And there were large differences in the anisotropy factors between both colon mucosa/submucosa at the same wavelength, there were also large differences in the anisotropy factors between both colon muscle layer/chorion at the same wavelength.There were large differences in the value ranges of the absorption coefficients, scattering coefficients and anisotropy factors between both colon mucosa/submucosa,and there were also large differences in these value ranges between both colon muscle layer/chorion. There are the same orders of magnitude in the absorption coefficients for four kinds of colon tissues. The scattering coefficients of these tissues exceed the absorption coefficients by at least two orders of magnitude.CONCLUSION: There were large differences in the three optical parameters between normal and adenomatous human colon mucosa/submucosa at the same laser wavelength, and there were also large differences in these parameters between both colon muscle layer/chorion at the same laser wavelength. Large differences in optical parameters indicate that there were large differences in compositions and structures between both colon mucosa/submucosa, and between both colon muscle layer/chorion.Optical parameters for four kinds of colon tissues are wavelength dependent, and these differences would be useful and helpful in clinical applications of laser and tumors photodynamic therapy (PDT).

Mass Stopping Power and Range of Protons in Biological Human Body Tissues (Ovary, Lung and Breast)

In this work, the mass stopping power and range of protons in biological human body tissues (ovary, lung and breast) were calculated at the energy ranging from 0.04 MeV to 200 MeV using the MATLAB Program. The data relating to the densities, average atomic number to mass number and excitation energy for the present tissues were collected from ICRU Report 46. The mass stopping power was calculated by the Bethe formula. Moreover, the simple integration (continuous slowing down approximation) method was employed for calculating protons range at the tissues. The results of the mass stopping power versus energy and the range versus energy were presented graphically and the empirical formulae for calculating the mass stopping power and the ranges were obtained. The present results for mass stopping powers and ranges were compared with the results obtained by others. Good agreements were found between them, especially at the energy ranging from 3 to 200 MeV.

THE EXPRESSIONS OF HBV X GENE AND ets-2, IGF-Ⅰ, c-myc AND N-ras ONCOGENES IN HUMAN HEPATOCELLULAR CARCINOMA AND TUMOR-ADJACENT TISSUES

The expressions of HBV X gene and ets-2, IGF-I, c-myc and N-ras were studied in 7 pairs of human primary hepatocellular carcinoma (PHC) and tumor-adjacent tissues, using RNA hybridization and im-munoblot methods. The results showed that specific 17 and 28 kD HBV X gene products (HBxAg) were existed in a portion of PHC and tumor-adjacent tissues. The 17 kD HBxAg was detected in the sera of 3 patients who also had 17 kD HBxAg in their liver tissues. Multiple expressions of oncogenes such as ets-2, c-myc and N-ras were observed in PHC and tumor-adjacent tissues that had HBxAg expressed, indicating HBxAg might function as a transactivator in the course of intracellular proto-oncogene activation. It is also observed that in some tumor-adjacnet tissues the expressions of ets-2, c-myc and N-ras were higher than those in corresponding PHC. The relationship of HBxAg to the expression of est-2, IGF-Ⅱ, c-myc and their possible roles in the carcinogenesis of PHC are discussed.

High resolution ultrastructure imaging of fractures in human dental tissues

Human dental hard tissues are dentine, cementum, and enamel. These are hydrated mineralised composite tissues with a hierarchical structure and versatile thermo-mechanical properties. The hierarchical structure of dentine and enamel was imaged by transmission electron microscopy （TEM） of samples prepared by focused ion beam （FIB） milling. High resolution TEM was carried out in the vicinity of a crack tip in dentine. An intricate ＂random weave＂ pattern of hydroxyapatile crystallites was observed and this provided a possible explanation for toughening of the mineralized dentine tissue at the nano-scale. The results reported here provide the basis for improved understanding of the rela- tionship between the multi-scale nature and the mechanical properties of hierarchically structured biomaterials, and will also be useful for the development of better prosthetic and dental restorative materials.

Bio-effects of 5th generation electromagnetic waves on organs of human beings

Objectives:The uses of devices of electromagnetic waves(EMWs)are increasing day by day.Similarly,the generation of the waves is increasing.The frequency spectrum of the generation of waves is also increased.In this manuscript,an analysis of the high frequency EMWs has been made by the electric fields generated due to the exposure of 5th generation(5 G)of mobile phones.Methods:Due to the emission of waves from the towers,the electric field is generated around the transmission tower of mobile phones.The electric fields are computed by the power of the transmission tower.The electric fields across the biological tissues/cells are also computed when the EMWs penetrate inside the body.The electric fields are made across the organs of different depths inside the body.Results:The induced electric fields inside the organs of the human beings are responsible for the absorption of energy from high frequency EMWs.The absorbed amount of energy from high frequency waves may become the cause of harmful effects on the life of organs of human beings.Conclusion:In this manuscript,after analysis of the computed electric fields inside the organs of human beings,it is concluded that the EMWs of 5 G spectrum of mobile phone towers may more harmful for the life of organs as 4th generation(4 G)spectrum of mobile phone waves.The energy absorption by the 4 G spectrum is lower than 5 G spectrum due to the range of frequency of waves.The effects on the pancreas,retina,skin,intestine,spleen,stomach and uterus are more than low water content organs like nails,bone,teeth etc.

Preliminary study of the correlation between trace elements in human hair, liver and kidney by proton induced X-ray emission analysis

This paper deals with the determination of trace elements in normal human hair, liver and kidney by Proton Induced X-ray Emission (PIXE) analysis. Sampling, specimen preparation and experimental procedures are described in detail. The accuracy of our system has been checked up with the determination of standard reference materials. The preliminary results on correlations between trace elements in human tissues are discussed. Application of the method described in the paper gives evidence in favour of the PIXE as a good tool on environmental life elements and health studies.

Preparation and in vitro studies of microencapsulated cells releasing human tissue inhibitor of metalloproteinase-2

Objective： To prepare microencapsulated cells releasing human tissue inhibitor ofmetalloproteinase-2 （TIMP-2）, and investigate their biological characteristics in vitro. Methods： Chinese hamster ovary （CHO） cells were stably transfected with a human TIMP-2 expression vector, encapsulated in barium alginate microcapsules and cultured in vitro. Morphological appearance of the microcapsules was observed under a light microscope. Cell viability was assessed using MTT （3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide） assay. Enzyme linked immunosorbent assay （ELISA） and reverse zymography were used to confirm the release of biologically active TIMP-2 from the microcapsules. Cryopreservation study of the microencapsulated cells was carried out using dimethyl sulfoxide （DMSO） as preservative agent. Results： The microcapsules appeared like a sphere with diameter of 300-600 ~tm. The surface of the capsule wall was clearly smooth. The microencapsulated cells survived well and kept proliferating over the 6 weeks observed. No significant difference in TIMP-2 secretion was found between encapsulated and unencapsulated cells. Reverse zymography confirmed the bioactivity of MMP （matrix metalloproteinase） inhibition of TIMP-2. The cryopreservation process did not damage the microcapsule morphology nor the viability of the cells inside. Conclusion： Microencapsulated engineered CHO cells survive at least 6 weeks after preparation in vitro, and secrete bioactive TIMP-2 freely from the microcapsules.

Comparative Proteome Analysis of Human Lung Squamous Carcinoma Tissue

Objective： To establish the two-dimensional electrophoresis profiles with high resolution and reproducibility from human lung squamous carcinoma tissue and paired normal tumor-adjacent bronchial epithelial tissue, and to identify differential expression tumor-associated proteins by using proteome analysis. Methods： Comparative proteome analysis with 20 human lung squamous carcinoma tissues and the paired normal bronchial epithelial tissues adjacent to tumors was carried out. The total proteins of human lung squamous carcinoma tissue and paired normal tumor-adjacent bronchial epithelial tissue were separated by means of immobilized pH gradient-based two-dimensional gel electrophoresis （2-DE） and silver staining. The differential expression proteins were analyzed and then identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF-MS）. Results： （1） Well-resolved, reproducible 2-DE patterns of human lung squamous carcinoma and adjacent normal bronchial epithelial tissues were obtained. For tumor tissue, average spots of 3 gels were 1567±46, and 1436±54 spots were matched with an average matching rate of 91.6%. For control, average spots of 3 gels were 1349±58, and 1228±35 spots were matched with an average matching rate of 91.03%. The average position deviation of matched spots was 0.924±0.128 mm in IEF direction, and 1.022±0.205 mm in SDS-PAGE direction; （2） A total of 1178±56 spots were matched between the eleetrophoretie maps of 20 human lung squamous carcinoma tissues and paired normal tumor-adjacent bronchial epithelial tissues. Seventy-six differentially expressed proteins were screened; （3） Sixty-eight differential proteins were identified by PMF, some proteins were the products of oneogenes, and others involved in the regulation of cell cycle and signal transduetion; （4） In order to validate the reliability of the identified results, the expression of 3 proteins mdm2, c-jun and EGFR, which was correlated with lung squamous carcinoma, was detected by immunohistoehemieal staining and Western blot analysis. The results revealed that mdm2, c-jun and EGFR were up-regulated in lung squamous carcinomas, whereas they were down-regulated in adjacent normal bronchial epithelial tissues, normal lung tissues and inflammatory pseudotumor, which was consistent with our proteome analysis results. Conclusion： The well-resolved, reproducible 2-DE patterns of human lung squamous carcinoma and adjacent normal bronchial epithelial tissues were established and 68 differential proteins were characterized by applying comparative proteome analysis successfully. These results will provide scientific foundation for screening the molecular biomarker used to diagnose and treat lung squamous carcinoma, as well as to improve the patient＇s prognosis and provide new clue for the research of lung squamous carcinogenic mechanism.

Vitamin D receptor expression in human bone tissue and dose-dependent activation in resorbing osteoclasts

The effects of vitamin D on osteoblast mineralization are well documented. Reports of the effects of vitamin D on osteoclasts, however, are conflicting, showing both inhibition and stimulation. Finding that resorbing osteoclasts in human bone express vitamin D receptor （VDR）, we examined their response to different concentrations of 25-hydroxy vitamin D3 [25（OH）D3] （100 or 500 nmol·L^-1） and 1,25-dihydroxy vitamin D3 [1,25（OH）2D3] （0.1 or 0.5 nmol·L^-1） metabolites in cell cultures. Specifically, CD14＋ monocytes were cultured in charcoal-stripped serum in the presence of receptor activator of nuclear factor kappa-B ligand （RANKL） and macrophage colony-stimulating factor （M-CSF）. Tartrate-resistant acid phosphatase （TRAP） histochemical staining assays and dentine resorption analysis were used to identify the size and number of osteoclast cells, number of nuclei per cell and resorption activity. The expression of VDR was detected in human bone tissue （ex vivo） by immunohistochemistry and in vitro cell cultures by western blotting. Quantitative reverse transcription-PCR （qRT-PCR） was used to determine the level of expression of vitamin D-related genes in response to vitamin D metabolites. VDR-related genes during osteoclastogenesis, shown by qRT-PCR, was stimulated in response to 500 nmol·L^-1 of 25（OH）D3 and 0.1-0.5 nmol·L^-1 of 1,25（OH）2D3, upregulating cytochrome P450 family 27 subfamily B member I （CYP27B1） and cytochrome P450 family 24 subfamily A member I （CYP24A1）. Osteoclast fusion transcripts transmembrane 7 subfamily member 4 （tm7sf4） and nuclear factor of activated T-cell cytoplasmic 1 （nfatcl） where downregulated in response to vitamin D metabolites. Osteoclast number and resorption activity were also increased. Both 25（OH）D3 and 1,25（OH）2D3 reduced osteoclast size and number when co-treated with RANKL and M-CSF. The evidence for VDR expression in resorbing osteoclasts in vivo and low-dose effects of 1,25（OH）2D3 on osteoclasts in vitro may therefore provide insight into the effects of clinical vitamin D treatments, further providing a counterpoint to the high-dose effects reported from in vitro experiments.

Construction and characterization of a cDNA library from human liver tissue with chronic hepatitis B

Objective: To construct a cDNA library from human liver tissue with chronic hepatitis B and check its quality for investigating the expression level of liver tissue infected by hepatitis B virus. This will then be used to find the relevant genes and interesting proteins associated with the development of hepatitis B. Methods: The total RNA from liver tissue with chronic hepa- titis B was extracted and the mRNA was purified using TRIZOL method. Switching mechanism at 5′ end of the RNA transcript (SMART) technique and CDS III/3′ primer were used for first-strand cDNA synthesis. Long distance polymerase chain reaction (LD PCR) was then used to synthesize the double-strand cDNA that was then digested by Sfi I and fractionated by CHROMA SPIN-400 column. The longer than 0.4 kb cDNAs were collected and ligated to λTriplEx2 vector. Then λ phage packaging reaction and library amplification were performed. The qualities of both unamplified and amplified cDNA libraries were strictly checked by conventional titer determination. Fourteen plaques were randomly picked and tested using PCR with universal primers derived from the sequence flanking the vector. Results: The titers of unamplifed and amplified libraries were 1.94×106 pfu/ml and 1.49×109 pfu/ml respectively. The percentages of recombinants from both libraries were 98.15% in unamplified library and 98.76% in amplified library. The lengths of the inserts were 1.23 kb in average, 1?2 kb in 64.29%, and 0.5?1.0 kb in 35.71%. Conclusion: A high quality cDNA library from human liver tissue with chronic hepatitis B was successfully constructed.

Ameliorative effects of human adipose tissue-derived mesenchymal stem cells on myelin basic protein-induced experimental autoimmune encephalomyelitis in Lewis rats

Mesenchymal stem cells have been previously shown to exert an immunomodulatory function. The present study sought to investigate the effects of multipotential human adipose tissue-derived mesenchymal stem cells （hAdMSCs） on disease progression and cytokine expression in Lewis rats with experimental autoimmune encephalomyelitis （EAE） induced by myelin basic protein. The duration of EAE paralysis in the group treated on day 7 posfimmunization with 5 × 10^6 hAdMSCs was significantly reduced compared with the vehicle-treated controls and the 1 x 106 hAdMSC- treated group. The duration of EAE paralysis in the groups treated with 5 × 10^6 hAdMSCs on both day 1 and day 7 postimmunization was significantly reduced compared with the vehicle-treated controls and the groups treated with 5 × 10^6 hAdMSCs on both day 7 and day 10 postimmunization. The mRNA expression of interleukin-10 and indoleamine 2, 3-dioxygenase was significantly decreased in the hAdMSC-treated group compared with the vehicle-treated group. These findings suggest that the ameliorative effects of hAdMSCs on EAE symptoms operate in a dose- and time-dependent manner and can be mediated in part by the ample production of anti-inflammatory cytokines.

Cherenkov radiation from electrons passing through human tissue

A method for investigating the optical properties of human tissues is suggested.The method is based on the measurement of Cherenkov radiation produced by relativistic electrons passing through the tissue.Monte-Carlo simulation of visible photon emission and propagation is carried out taking into account multiple electron and photon scattering processes.Sensitivity of the Cherenkov radiation to the optical characteristics of human tissues is demonstrated.

PRELIMINARY COMPARISON OF SENSITIVITY TOWARD PARVO VIRUS H-1 OF HUMAN HEP ATOM A CELLS AND PARAHEPATOMA TISSUE

Preliminary observations on the result of infection by parvovirus of primary cultured cells of human hepatoma and parahepatoma tissue were reported. Human hepatoma and parahepatoma tissue were obtained by the culture method of tissue fragment plating. It was observed that their respective sensitivity to parvovirus H-1 was different. H-1 had inhibitory effect on epithelial cells of hepatoma tissue but without any significant effect on fibroblasts simultaneously, H-l had no effect on epithelial cells and fibroblasts of parahepatoma tissue. Further investigation of the relationship between parvovirus and hepatoma would be helpful not only in elucidating the mechanism of carcinogenesis and its suppression but also in the search of new approach for the treatment of hepatoma.

A NEW METHOD TO CONSTRUCT A FULL-LENGTH cDNA LIBRARY OF HUMAN NORMAL BLADDER TISSUE

Objective Using template switch mechanism at the 5’ end of mRNA technique (SMART) to construct a full length cDNA library of human normal bladder tissue. Methods The novel procedures used the template switching activity of powerscript reverse transcriptase to synthesize and anchor first strand cDNA in one step. Following reverse transcription, 5 cycles of PCR were performed using a modified oligo(dT) primer and an anchor primer to enrich the full length cDNA population with 1.0 g human normal bladder poly(A) + RNA, then double strand cDNA was synthesized. After digestion with sfiI and size fractionation by CHROMA SPIN 400 columns, double strand cDNA was ligated into λ TripIEx 2 vector and was packaged. We determined the titer of the primary library and the percentage of recombinant clones and finally amplified the library. Results The titer of the cDNA library constructed was 2.1×10 6 pfu·mL -1 , and the amplified cDNA library was 6×10 11 pfu·mL -1 , the percentage of recombination clones was 99%. Conclusion Using SMART technique helps us to construct full length cDNA library with high efficiency and high capacity which lays solid foundation for screening target genes of bladder diseases with probes and antibodies.

Human amniotic membrane and nerve tissue engineering

Totally three articles focusing on ＂the effects of microenvironment for human amniotic epithelial cell transplantation on cell survival and differentiation, the migration of human amniotic epithelial cells after in vitro transplantation, and the rheological characteristics of anastomosing injured sciatic nerve with human amniotic membrane without amniotic epithelial cells＂ are published in three issues. We hope that our readers find these papers useful to their research.

Effects of transforming growth factor β2 and connective tissue growth factor on induction of epithelial mesenchymal transition and extracellular matrix synthesis in human lens epithelial cells

AIM:To Investigate the effects of transforming growth factorβ2(TGF-β2)and connective tissue growth factor(CTGF)on transdifferentiation of human lens epithelial cells(HLECs)cultured in vitro and synthesis of extracellular matrix(ECM).METHODS:HLECs were treated with TGF-β2(0,0.5,1.0,5,10μg/L)and CTGF(0,15,30,60,100μg/L)for different times(0,24,48,72h)in vitro and the expression ofα-smooth muscle actin(α-SMA),the main component of the extracellular matrix typeⅠcollagen(Col-1)and fibronectin(Fn)were measured by using real-time polymerase chain reaction(PCR)and western-blot.RESULTS:TGF-β2 and CTGF significantly increased expression ofα-SMA mRNA and protein(P【0.05,P【0.001),Fn mRNA and protein(P【0.001),Col-1 mRNA and protein(P【0.001).TGF-β2 could induce HLECs expression of CTGF mRNA and protein in dosedependent manner(P【0.05,P【0.001).TGF-β2 and CTGF could induce HLECs to expressα-SMA,Fn and Col-1 in time-dependent manner.Each time of TGF-β2and CTGF induced HELCs expression ofα-SMA,Fn,Col-1 mRNA and protein was significant increase compared with control(P【0.05,P【0.001).CONCLUSION:TGF-β2 and CTGF could induce HLECs epithelial mesenchymal transition and ECM synthesis.

AB093.Ocular tissues bank for vision health research

Background:This infrastructure delivers biological material necessary for several research projects to Vision Health Research Network investigators(VHRN).Methods:Héma-Québec is the organism in charge obtaining consent and retrieving donor eyes for patient treatment or for research.In Quebec City,donor eyes are sent to the eye bank of the“Centre Universitaire d’Ophtalmologie”(CUO)of Saint-Sacrement hospital.Technicians at the eye bank evaluate the quality of the tissues.Those unfit for graft are transferred to the infrastructure where the coordinator encodes samples prior to their distribution.Results:Between 2013 and 2017,27 fundamental investigators,clinical investigators and collaborators supported by 60 students,trainees and laboratory assistants used this infrastructure to move forward their projects.Since 2013,results from those projects generated 21 scientific publications and 232 presentations.The infrastructure helped VHRN investigators obtain near 4 million dollars in grants from many organisms(CIHR,NSERC,Foundations,etc.).These grants allowed recruitment and formation of highly qualified personnel.Last year(April 2016 to March 2017),189 corneas and 23 eyes transited through the infrastructure.Conclusions:This infrastructure is available for all investigators that are members of the VHRN.Many original projects have been elaborated thanks to the human ocular tissues provided by this infrastructure.These projects will advance our knowledge in vision health.A better understanding of eye functions will lead to new treatments for eye diseases.

Orthotopical transplantation of human renal carcinoma tissue into nude mice and the establishment of a high metastatic cell line MRCC

Objective To establish a SOI model of human renal carcinoma and a high metastatic cell subline. Methods A human renal cell line RCC-9863 has been established by inoculating a human renal tumor tissue into nude mice s. c.. When RCC-9863 passaged for 20 times, the tissue from the same xemotransplant tumor were used to construct SOI model. Cultured the metastatic tissue in vitro, the tumor cell suspension was then injected orthotopically, The metastatic tissue obtained underwent the same procedure again. At last, the metastatic tumor was cultured in vitro and cloned. Results 15 days later, a tumor mass sized 1. 7 cm × 0. 6 cm in the nude mouse’s renal parenchyma was grown which lobulated, rude, and with multiply blood vessels and 55 days later later the mouse became moribund and metastases in the lungs were formed. The transplanted renal tumor in the SOI model grew fast and invasively and metastasized to lungs, lymphatic node and liver. A subline, MRCC, with metastatic ability to the lung was selected.

A benchtop brain injury model using resected donor tissue from patients with Chiari malformation

The use of live animal models for testing new therapies for brain and spinal cord repair is a controversial area. Live animal models have associated ethical issues and scientific concerns regarding the predictability of human responses. Alternative models that replicate the 3 D architecture of the central nervous system have prompted the development of organotypic neural injury models. However, the lack of reliable means to access normal human neural tissue has driven reliance on pathological or post-mortem tissue which limits their biological utility. We have established a protocol to use donor cerebellar tonsillar tissue surgically resected from patients with Chiari malformation(cerebellar herniation towards the foramen magnum, with ectopic rather than diseased tissue) to develop an in vitro organotypic model of traumatic brain injury. Viable tissue was maintained for approximately 2 weeks with all the major neural cell types detected. Traumatic injuries could be introduced into the slices with some cardinal features of post-injury pathology evident. Biomaterial placement was also feasible within the in vitro lesions. Accordingly, this ‘proof-of-concept’ study demonstrates that the model offers potential as an alternative to the use of animal tissue for preclinical testing in neural tissue engineering. To our knowledge, this is the first demonstration that donor tissue from patients with Chiari malformation can be used to develop a benchtop model of traumatic brain injury. However, significant challenges in relation to the clinical availability of tissue were encountered, and we discuss logistical issues that must be considered for model scale-up.

Site-directed Mutagenesis Based on Overlap Extension PCR

[Objective] To establish an efficient, convenient and economical method for site-directed mutagenesis. [Method] The target mutation was introduced into primers designed by DNAMAN5.0 software. Through overlap extension PCR for twice obtained the mutation gene which of the full length of the recombinant Human Tissue type plasminogen activator （Reteplase）. The mutation gene cloned it into pEASY- blunt simple cloning vector for sequencing. [Result] The sequencing results showed that three site mutations were fully consistent with the expected results （10~ site had been added a base-pair of A, C had been changed into G at 137~ site, G had been changed into A at 686~ site）.Three site mutations were introduced by using overlap extension PCR on one-step. The overall rate of obtaining the mutant sites was 100%. Site-directed mutagenesis will clone the recombinant Human Tissue type plas- minogen activator and laid the basis for the functional study. [Conclusion] Site-directed mutagenesis was successfully implemented based on the overlap extension PCR which is an efficient, convenient and economical DNA-directed mutagenesis method.