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Biomedical subjects

B E Jarrell

Publications and source records attributed to B E Jarrell.

At least 55 records · Page 3Linked to original sources
PubMed1989

Enhanced adherence of human adult endothelial cells to plasma discharge modified polyethylene terephthalate.

Human adult aortic endothelial cell attachment to polyethyleneterephthalate (PET as mylar film) was examined in vitro. PET was examined in both the unmodified form (PET-) and in a modified form (PET+) that had undergone plasma discharge surface modification (PDSM). These surfaces were compared to unmodified tissue culture polystyrene (PS-). The kinetics of attachment and the force of attachment using the rotating disc were determined as a function of surface and substrate protein applied to the surface. Four proteins--fibronectin, collagen I/III, collagen IV/V, and laminin--were added and compared to saline pretreatment. The most significant variable affecting attachment was the time of incubation. When corrected for time, PET+ demonstrated significantly superior attachment kinetics when compared to PET- in most cases. These kinetics were similar to those seen on PS-. Fibronectin precoating of the surface greatly enhanced attachment kinetics on PET+ and PS- but to a much lesser degree on PET-. The fibronectin effect was synergistic with PDSM, suggesting that PDSM enhances protein adsorption on the surface. The force of attachment was generally independent of incubation time and surface/substrate combination except for laminin precoating. Taken together, these data indicate that human endothelial cell adherence to PET may be significantly enhanced by PDSM and surface precoating with fibronectin. Attachment occurs rapidly and, once attached, the cells demonstrate a very firm attachment force capable of resisting shear stresses up to 90 dynes/cm2.

Cell Adhesion↗
PubMed1989

Intravital fluorescence microscopy of endothelial cells on vascular grafts.

The ability to evaluate the extent of initial endothelial cell coverage on a vascular graft subsequent to an endothelial cell seeding technique would be desirable to substantiate the durability of the endothelial cell lining. To this end, we have evaluated the use of intravital fluorescence microscopy to assess human endothelial cell interaction with vascular grafts. Five fluorescent stains, mithramycin, Hoechst 33342, sulfofluorescein diacetate, Nile red, and rhodamine 123 were evaluated for their ability to fluorescently label human endothelial cells. The staining capability of each dye was also evaluated with respect to accuracy in determining seeded cell number and cell spreading. Of the stains evaluated, rhodamine 123 produced the most desirable characteristics. We observed excellent cell visualization after a 30-min incubation. Unlike the other four stains, rhodamine 123 exhibited a bright orange fluorescence emission at a 510-nm excitation wavelength while the underlying dacron or expanded polytetrafluoroethylene demonstrated minimal autofluorescence. Rhodamine 123 also exhibited no inhibitory effect on cell attachment to plastic or subsequent cell growth in culture. Intravital fluorescence microscopy could be easily utilized in the operating room to visualize part or all of an endothelial cell-seeded graft prior to implantation and would permit a quantitative as well as qualitative evaluation of the seeding process. Since intravital fluorescence imaging does not require tissue fixation, the same surface as that evaluated for seeding efficiency can be directly implanted.

Blood Vessels↗
PubMed1989

Effects of in vitro aging on human endothelial cell adherence to dacron vascular graft material.

The adherence and growth characteristics of cultured human adult large vessel endothelial cells (EC) maintained on substrate-coated polyethylene terephthalate in the form of woven dacron vascular graft were examined. Two different populations of EC, a low passage (EC (low] and a high passage (EC (high] population, were incubated at cell densities from 10(3) to 10(5) EC/cm2 for 24 hr. Cell counts were performed at 24 hr and after 14 days in tissue culture. At 24 hr on collagen I/III-coated Dacron, EC adherence was independent of the number of passages or the incubation density. When examined after 14 days in culture only EC (low) incubated at 10(5) EC/cm2 maintained initial cell numbers. Human plasma precipitated upon Dacron was necessary before significant cell growth occurred. We conclude that increasing in vitro EC age is associated with decreasing attachment and growth on Dacron. Growth on this important vascular replacement surface requires low passage EC incubated at a high density and the presence of plasma proteins in the substrate coating.

Blood Platelets↗
PubMed1989

Human microvessel endothelial cell isolation and vascular graft sodding in the operating room.

We have evaluated multiple factors inherent to an operating room-compatible endothelial cell procurement and sodding procedure. Microvessel endothelial cell isolations have been performed on fat tissue obtained from over 140 patients with a 100% success rate. Liposuction-derived fat was optimal with respect to cell yield, and isolation time. The devices and equipment used were acceptable to the operating room and the complete cell procurement procedure was successful even in the hands of personnel with minimal training. Fat digestion was achieved using crude clostridial collagenase, with an average cell yield of 1 x 10(6) microvessel endothelial cells/gm of fat. Evaluation of this procedure with canine fat using an operating room acceptable procedure resulted in a 100% procurement success rate requiring 1.5 hours (+/- .5 hrs) for completion of the fat isolation, and cell isolation procedure. Microvessel EC could subsequently be used in graft seeding or sodding techniques to establish endothelial cell monolayers on vascular grafts. Our results indicate that one person with minimal cell isolation background can reproducibly isolate large quantities of sterile autologous endothelial cells in the operating room for immediate use in endothelial cell seeding/sodding procedures.

Adipose Tissue↗
PubMed1989

Endothelial cell interactions with native surfaces.

Since native vessels are presumably the ideal surface for endothelial cells, we have examined endothelial cell interactions with natural surfaces as a standard to determine the possibilities obtainable on a surface. We have examined three separate types of natural surfaces including human amnion, superficially-injured human arteries, and tanned bovine carotid arteries. When basement membrane collagen is a principal component of a surface, such as with amnion or a superficially denuded large vessel, very rapid cell attachment and spreading occurs. Intact confluent monolayers covering 100% of the amnion surface are present as early as one hour. Human arteries superficially injured to denude their endothelium also exhibit excellent affinity for EC adherence and spreading. Endothelial monolayers cover 80.8% (+/- 5.3) of this surface after one hour, with 91.4% (+/- 1.2) coverage after two hours. For tanned bovine carotid arteries, one and two hour endothelial cell incubation results in coverage of 59.2% (+/- 1.3) and 75.9% (+/- 4.1), respectively. This surface is composed of interstitial collagen of the arterial wall in medial and adventitial layers. Electron microscopy reveals excellent endothelial cell spreading with little or no exposed underlying basement membrane. This suggests that polymeric surfaces designed to mimic injured native surface could allow an endothelialized surface to develop within minutes to hours.

Amnion↗
PubMed1989

Endothelialization of vascular prosthetic surfaces after seeding or sodding with human microvascular endothelial cells.

The rapid establishment of an endothelial cell (EC) monolayer on the luminal surface of small-diameter vascular grafts may be necessary to prevent early thrombosis and failure. We have studied procedures used to promote EC coverage of vascular grafts and have compared preclotting prosthetic surfaces with ECs in platelet-rich plasma (seeding) with plating ECs onto a preestablished clot (sodding). We evaluated the rate of monolayer formation, the subsequent resistance to shear stress, and the effects of EC growth factors (ECGF and heparin) on these functions. Woven Dacron was seeded or sodded at a density of 2 x 10(5) cells/cm2 with human adult microvessel ECs derived from adipose tissue. In the presence of ECGF-heparin, the immediate establishment of an EC layer after sodding was observed, whereas seeded grafts required almost 48 hours for cells to reach the surface. In the absence of ECGF-heparin, sodded grafts still exhibited a complete monolayer of EC, whereas ECs were not observed at the surface of seeded grafts after 48 hours. After exposure to shear stress (up to 20 dynes/cm2) for 2 hours, most freshly sodded EC remained attached; however, the loss of loosely adherent cells did occur. EC seeded grafts remained covered with fibrin matrix after exposure to shear stress. We conclude that the use of a microvessel sodding technique as an alternative to previously reported seeding techniques is necessary for the immediate formation of an EC monolayer before implantation.

Blood Vessel Prosthesis↗
PubMed1988

Insertion and recovery of a new retrievable vena caval filter. Work in progress.

A new retrievable inferior vena cava (IVC) filter was tested in nine pigs. Insertion was through a 14 French sheath using both the femoral and jugular approaches. All insertions were successful, and there was a 100% postinsertion IVC patency rate (8/8 pigs at one week and 1/1 pig at one month). Addition of an apical hook to the filter design allowed transjugular retrieval of two filters at one week postinsertion. Three of nine filters migrated to the upper IVC. The filter's design allows paraxial blood flow despite trapped thrombus and inhibits filter tilting. In vitro, the filter captured 95% to 100% of 5 X 5 mm clots. If problems with migration can be solved, the new filter may provide effective short- and long-term prophylaxis against pulmonary embolism.

Animals↗
PubMed1988

Kinetics of endothelial cell-surface attachment forces.

Physical and biochemical forces exist that are necessary for the persistent attachment and function of ECs on native and prosthetic blood vessels. The optimization of conditions that permit regeneration of these attachment forces may allow rapid establishment of a durable, biocompatible EC monolayer. We examined the effects of three major factors, protein substrate, EC incubation time, and shear stress, on the attachment kinetics of human adult ECs to two different polymers. ECs were incubated up to 30 minutes on polymers (PS or PET) coated with extracellular matrix proteins: collagen I/III, fibronectin, collagen IV/V, laminin, gelatin, or saline control. After incubation, continued attachment in the presence of shear stress (created in a rotating disc device) between zero and 90 dynes/cm2 for 30 minutes was evaluated. Maximal adherence was observed on all substrates by 30 minutes. Therefore, after a 30-minute incubation, the percentage of cells attached (postshear ECs/preshear ECs/preshear ECs X 100) was measured as a function of shear stress. ECs attached to a matrix of fibronectin or collagen I/III demonstrated shear-resistant adherence after as little as 5 minutes of static incubation before initial shear exposure. By 30 minutes, more than 90% of the ECs on both matrices demonstrated the ability to remain attached in the presence of 90 dynes/cm2 of shear stress. We conclude that forces that attach ECs to surfaces are affected by temporal factors (incubation time) and substrate composition and may be quantified with a defined shear stress detachment assay. Understanding and manipulating these temporal physiochemical parameters should allow one to re-create an optimal EC monolayer on a blood-contacting surface.

Adhesiveness↗
PubMed1987

Cytogenetic evaluation of human endothelial cell cultures.

Cytogenetic evaluation of serially subcultivated human endothelial cells revealed significant differences between cultures derived from fetal umbilical cords and cultures derived from various vessel sites in adults. A rapid increase in the prevalence of polyploid cells, to levels of 100% in many cases, was detected in human umbilical vein endothelial cell cultures but not in endothelial cell cultures from adult vessels. Because the development of polyploidy has been viewed as one signpost of in vitro senescence, it may be that these in vitro observations of high levels of polyploidy are a reflection of the fact that umbilical tissue is at the end of its in vivo developmental lifespan when studied. Consistent karyotypic alterations also were observed in two clones from adult human abdominal aorta, even though these cultures exhibited low percentages of polyploid cells. Cultures of one clone exhibited a trisomy of chromosome 11, on which there are at least three onc gene loci, and a deletion of chromosome 13 through band q14. A loss of band 13q14 is a prezygotic chromosomal lesion known to predispose to retinoblastoma. In the other clone, two cell populations were observed, and each displayed a chromosomal abnormality. A trisomy of the long arm of chromosome 2 was noted in one cell population via a marker chromosome involving 2 and 14. The other cell population exhibited an abnormality of chromosome 2. Neither of these karyotypic alterations was detected in the parent culture from which the clones were derived. The results reported in this study have both practical and theoretical implications. The high incidence of polyploidy in serially cultivated umbilical cultures as well as the occurrence of chromosomal changes in umbilical and aortic cultures testify to the need for cytogenetic monitoring of cell cultures even though they are derived from presumably normal tissue. Cytogenetic changes in the endothelium may be important in atherogenesis and other pathologic states. The conversion of diploid endothelial cells into polyploid endothelial cells may provide a convenient model cell system for studying mechanisms of the development of polyploidy in cells and their relationship to in vitro senescence.

Adult↗
PubMed1987

Complications encountered with the use of the Greenfield filter.

The Greenfield filter can be used with a low complication rate provided one adheres to certain principles. First, preoperative venography to define the inferior vena caval anatomy will help avoid difficulties associated with anatomic variations. At the time the study is carried out, it would be extremely useful if the radiologist places a radiopaque marker at the level of the renal veins. This will ensure that filters will be placed in the infrarenal position when appropriate, thus preventing occasional inadvertent discharge, particularly into the right renal vein. Second, use of a guide wire greatly facilitates passage of the introducer and accurate intracaval positioning. Third, intraoperative technical errors must be recognized and promptly corrected. Finally, meticulous postoperative follow-up is essential, and recurrent embolism or any change in filter position requires repeat roentgenography of the vena cava to guide appropriate corrective treatment.

Filtration↗
PubMed1987

Initial adherence of human capillary endothelial cells to Dacron.

Successful endothelialization of vascular grafts by seeding with endothelial cells (EC) at implantation is related to the number of EC which initially adhere to the graft. Using an in vitro system we examined the initial adherence of EC from human perinephric fat capillaries to woven Dacron that was either unmodified or precoated with several substrates. We studied capillary EC because they have not been investigated as a source of EC for graft seeding, although transinterstitial capillary ingrowth is one possible mechanism for spontaneous graft endothelialization. EC were isolated using collagenase and characterized morphologically and functionally including positive factor VIII-related antigen staining. EC were studied at three phases in culture: (A) primary EC with no subcultivations (EC-0); (B) EC after two subcultivations with trypsin (EC-2); and (C) EC after 10 subcultivations with trypsin (EC-10). EC were seeded onto graft material at a density of 10(5) cells/cm2 (100% confluence) and examined for cell counts and morphology after one day in culture by light and electron microscopy. Results are as follows: (table; see text) The conclusions are: (1) All capillary EC demonstrated adherence to Dacron, but this initial adherence was strongly influenced by graft pretreatment with collagen or plasma. (2) Serially subcultivated EC (EC-2 and EC-10) had significantly higher initial adherence to pretreated Dacron compared to the primary cells (EC-0) (P less than .05). This suggests that briefly cultured and subcultivated EC have superior initial adherence characteristics to treated dacron compared to primary EC with no subcultivations. (3) Fat capillary EC are easily procured and cultured and provide a rich source of human EC for endothelializing vascular prostheses.

Blood Vessel Prosthesis↗
PubMed1987

Dynamics of erythropoiesis following renal transplantation.

We examined the temporal dynamics of the correction of anemia following renal transplantation in 65 recipients using a sensitive radioimmunoassay for erythropoietin to determine the effects of modern immunosuppressive agents, delayed graft function, and early acute rejection. Pretransplant mean erythropoietin (25.6 +/- 3.3 mU/ml) was only 25% of the expected value at the mean hematocrit of 27.2 +/- 0.7, and erythropoietin correlated positively with hematocrit (r = 0.37, P less than 0.05). Following onset of graft function, erythropoietin increased to 109 +/- 13 mU/ml and then decreased in a negative feedback fashion over the next several months. Delayed graft function was associated with delay in the assumption of this orderly process irrespective of the immunosuppressive regimen used. Cyclosporine A produced a biphasic response despite delayed graft function in recipients with underlying adult polycystic kidney disease. Correction of anemia required resumption of graft function. Onset of acute graft rejection within the first month posttransplantation (14 episodes in 11 patients) abrogated the hematopoietic response until the rejection was successfully reversed. We conclude that a major cause for the anemia of renal failure is subnormal production of erythropoietin. Following transplantation, anemia corrects in an orderly manner with restoration of the normal biofeedback process between erythropoietin and red cell mass. This process is delayed by failure of graft to function initially and interrupted by acute early rejection, re-commencing following successful reversal.

Adolescent↗