Objective To study the preparation method of acellular vascular matrix and to evaluate its biocompatibil ity and safety so as to afford an ideal scaffold for tissue engineered blood vessel. Methods Fresh caprine carotids (length, 50 mm) were harvested and treated with repeated frozen (—80 )/thawing (37℃), cold isostatic pressing (506 MPa, 4 ), and 0.125% sodium dodecyl sulfate separately for preparation of acellular vascular matrix. Fluorescence staining and DNA remain test were used to assess the cell extracting results. Biological characteristics were compared with the raw caprine carotids using HE staining, Masson staining, scanning electron microscope (SEM), and mechanical test. Biocompatibil ity wasdetected using cell adhesion test, MTT assay, and subcutaneously embedding test. Ten SD rats were divided into 2 groups (n=5). In experimental group, acellular vascular matrix preserved by the combination of repeated frozen/thawing, ultrahigh pressure treatment and chemical detergent was subcutaneously embedded; and in control group, acellular vascular matrix preserved only by repeated frozen/thawing and ultrahigh pressure treatment was subcutaneously embedded. Results HE staining and Masson staining revealed that no nucleus was detected in the acellular vascular matrix. SEM demonstrated that a lot of collagen fibers were preserved which were beneficial for cell adhesion. Fluorescence staining and DNA remain test showed that the cells were removed completely. There was no significant difference in stress and strain under the maximum load between before and after treatment. Mechanical test revealed that the acellular vascular matrix reserved mechanical properties of the raw caprine carotids. Cell adhesion test and MTT assay confirmed that cytotoxicity was grade 0-1, and the acellular vascular matrix had good compatibil ity to endothel ial cells. After subcutaneously embedding for 8 weeks, negl igible lymphocyte infiltration was observed in experimental group but obvious lymphocyte infiltration in control group. Conclusion The acellular vascular matrix, which is well-preserved by the combination of repeated frozen/thawing, ultrahigh pressure treatment, and chemical detergent, is an ideal scaffold for tissue engineered blood vessel.
Objective To investigate the feasibil ity of preparing the porous extracellular matrix (ECM) by use of some chemicals and enzymes to decellularize the porcine carotid artery. Methods The porcine carotid artery was procured, and warm ischemia time was less than 30 minunts. The porcine carotid artery was decellularized with 1% sodium dodecyl sulfate (SDS) for 60 hours to prepare common ECM; then common ECM was treated with 0.25% trypsin (for 6 hours) and 0.3 U/ mL collagenase (for 24 hours) to prepare porous ECM. The common ECM and porous ECM were stained with HE,Masson’s trichrome, and Orcein to evaluate the histological features. Then the mechanical property, cytotoxicity, and pore size of ECMs were determined. After 4 weeks of subcutaneous implantation in dogs, the histological examination was used for the study. Results Histological observation confirmed that 2 kinds of ECMs were decellularized completely and more porous structure was observed in porous ECM. Scanning electron microscope showed the pores in porous ECM were greater and the length of shorter axis in porous ECM ranged from 5 to 30 μm, the length of longer axis from 40 to 100 μm. The porosity of porous ECM (99.25%) was greater than that of common ECM (91.50%). The burst pressure of porous ECM decreased when compared with common ECM, showing significant difference [(0.154 3 ± 0.012 7) MPa vs [0.305 2 ± 0.015 7) MPa, P lt; 0.05]. There was no significant difference in suture retention strength between 2 kinds of ECMs (P gt; 0.05). The cytotoxicity test showed no obvious cytotoxicity in 2 kinds of ECMs. In vivo implantation test showed that the deeper host cells infiltration and more neo-microvessels in porous ECM were observed than in common ECM. Conclusion SDS and some enzymes can be used to prepare porous ECM as the scaffold for tissue engineered blood vessels.
Objective To observe the adhesion and prol iferation of late endothel ial progenitor cells (EPCs) planted on nanoporous PLLA scaffold in vitro and to provide a new approach that optimizes tissue engineered material. Methods Male and female New Zealand rabbits (weight 2.5-3.0 kg) were used. Isolated late EPCs from rabbit peri pheral blood were cultured. Electrostatic spinning technique was adopted to prepare misal igned nanofibers, al igned nanofibers and super-al igned nanofibers, and low temperature plasma technique was appl ied to prepare misal igned membrane, al igned membrane and super-al igned membrane. After being divided into group A (cells only), B (misal igned membrane), C (normal membrane), D (al igned membrane) and E (super-al igned membrane), the primary late EPCs (1 × 105/mL) werecultured on scaffolds and MTT method was used to detect cell prol iferation abil ity at 3, 5, 7, 9, 11, 13, 15 and 17 days afterculture. After being divided into group A (misal igned membrane), B (normal membrane), C (al igned membrane) and D (superal igned membrane), precipitation method was appl ied to detect cell adhesion rate at 4, 12 and 24 hours after compound culture, and the morphologic changes of cells were observed at 4, 24 and 72 hours after compound culture. Results Fiber diameters in nanofibrous PLLA scaffolds were 300-400 nm, with a porosity rate of above 90%. At 3, 5, 7, 9, 11, 13, 15 and 17 days after culture, A value of each group was increased with time and the cells in each group grew well, showing there was no significant difference between group A and group B at each time point (P gt; 0.05 ); during the period of 7-15 days after culture, the difference between groups C, D and E and groups A and B was significant (P lt; 0.05). At 4 hours after compound culture, the adhesion rate of group A was superior to that of groups B, C and D (P lt; 0.05); at 12 and 24 hours after compound culture, the adhesion rate of groups B, C and D was remarkably higher than that of group A (P lt; 0.05); significant difference was noted in each group between the time point of 4 hours and the time point of 12 and 24 hours after compound culture (P lt; 0.05), but no significant difference between 12 hours and 24 hours was detected (P gt; 0.05). Morphology observation demonstrated that cells grew well on the scaffolds, the cells in groups A and B grew sporadically and disorderly, while the cells in groups C and D attached and al igned along fiber and prol iferated, with an excretion of ECM. Group D was better at maintaining cell morphology. Conclusion Al igned and superal igned nanofibers of PLLA scaffold can promote the adhesion and prol iferation of seed cells on the scaffold and maintain good cell morphology, which is an appropriate candidate scaffold material for blood vessel tissue engineering. Late EPCs is an ideal cell source for blood vessel tissue engineering.
To study the feasibil ity of human adipose derived stem cells (ADSCs) in monolayer culture induced into smooth muscle cells in vitro as seeding cells in vascular tissue engineering. Methods The mononuclear cells in human adipose were separated by collagenase treatment and seeded on culture dishes with the density of 5 × 105/cm2. Cellswere cultured in M-199 plus 10% FBS. When reaching confluence, the cells were subcultured by 0.1% trypsin and 0.02%EDTA treatment, PDGF-BB (50 ng/mL) and TGF-β1 (5 ng/mL) were added at the passage 1 to enhance the smooth muscle cells’ phenotype. Cells were cultured under the inducing medium for 14 days. The morphology of induced cells was observed under the microscope. Cellular immunofluorescence and RT-PCR were used to determine the expression of smooth muscle cell markers of the post-induced cells. Flow cytometry (FACs) was used to examine the positive rate of induced team. Results Cocultured in M-199 media including TGF-β1 and PDGF-BB, the prol iferating capabil ity of the induced cells was significantly downregulated compared with the uninduced cells(P lt; 0.01). The induced cells exhibited “Hill and Valley” morphology, while the uninduced cells were similar to ADSCs of P0 which had the fibroblast-l ike morphology. The results of immunofluorescence indicated that the induced cells expressed smooth muscle (SM) cell- specific markers including α-smooth muscle actin (α-SMA), SM-myosin heavy chain (SM-MHC) and Calponin. The results of RT-PCR revealed that the induced cells also expressed α-SMA, SM-MHC, Calponin and SM-22α.The positive rates of α-SMA, SM-MHC and Calponin in FACs were 3.26% ± 1.31%, 3.55% ± 1.6% and 4.02% ± 1.81%, respectively, before the cells were induced. However, 14 days after the cell induction, the positive rates were 48.13% ± 8.31%, 45.33% ± 10.68% and 39.13% ± 9.42%, respectively. The positive rates in induced cells were remarkably higher than those in uninduced cells(P lt; 0.01). Conclusion The human ADSCs can be induced to express vascular smooth muscle markers, and they are a new potential source of vascular tissue engineering.