[Culture of human cartilage tissue using a perfusion chamber]

In the field of otolaryngology cartilage grafting is commonly performed to reconstruct skeletal defects. Knowledge of chondrocyte growth and differentiation can now be used to engineer cartilage tissue for grafting. The first condition is that chondrocytes maintain their differentiated phenotype besides being able to produce a new cartilage matrix. The target of this study was to develop a three-dimensional culture system for in-vitro formation of vital cartilage transplants. Chondrocytes were isolated by digesting the cartilage matrix with collagenase and hyaluronidase. After embedding in "low-melting" agarose, the chondrocytes were placed into a perfusion culture chamber to provide a constant supply of nutrients to the cultures. The peristaltic pump was operated with on/off intervals of 30 min. Ham's F12 supplemented with 2% FCS and 50 micrograms/ml ascorbic acid was employed as culture medium. Monoclonal antibodies specific to collagens type I and type II were used to characterise cells and matrix synthesis. Synthesis of proteoglycans and collagens was achieved using toluidine blue and azan staining. Under the described culture conditions, the chondrocytes maintained a differentiated phenotype (expression of collagen type II) with synthesis of collagens and proteoglycans. An accumulation of matrix products was achieved pericellularly. After 2-8 weeks the obtained tissue exhibited an excellent histological appearance showing the typical features of cartilage tissue. The results show that the perfusion chamber allows a quick in-vitro fabrication of a piece of pure cartilage tissue for transplantation.

Effect of growth factors on cell proliferation by human nasal septal chondrocytes cultured in monolayer

In the field of reconstructive surgery, autologous cartilage grafting is commonly performed to reconstruct skeletal defects. Because of the limited supply of fresh autologous cartilage many investigators concentrate on in vitro production of cartilage tissue. Several growth factors regulate the metabolism and activation of cartilage cells. In order to enhance the culture conditions for cartilage cells, the aim of our investigations was to characterize the influence of transforming growth factor (TGF)-beta, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) on the proliferation of differentiated human nasal septal chondrocytes. The isolated cells were cultured in monolayer using DMEM with and without 10% FCS. The cell proliferation was assessed using tritiated thymidine. We measured an increase of the proliferation rates when the different growth factors were added. The most important stimulatory effect was due to bFGF and the less to EGF. If all growth factors were added together a fivefold increase in the proliferative activity of the cells was achieved. The effects were further enhanced by factors present in fetal calf serum. We conclude that the culture conditions for cell expansion for cartilage engineering can be optimized employing growth factors.

Immunohistological studies of complement activation after xenogeneic perfusion of a working heart model

Transplantation of organs from one species to another leads to immediate hyperacute rejection. Activation of complement is one important factor involved in this process. Whether complement activation is induced by preformed natural antibodies (PNAbs) via the classical pathway or by an "activator surface" via the alternative pathway is unclear. In order to simulate the relevant clinical situation of animal donor/human recipient we perfused working porcine hearts ex vivo with human blood. This also offered the possibility to study the process of complement activation in a precisely defined system with human complement proteins. PNAb titer and complement lytic activity of the plasma were measured. Immunohistological stainings for IgG, IgM, C1q, C4, C3d, C5-9, factor B, and properdin were performed on tissue sections of the left ventricle. PNAb titer almost totally disappeared within the first 5 min of perfusion. Complement lytic activity of the classical pathway decreased similarly within the first 3 h of xenogeneic and autologous perfusion from 70% to 40%. More detailed immunohistological studies revealed positive staining for C3d on endothelium and myocardium of ex vivo perfused xenogeneic hearts. Complement-induced cytotoxicity was proven by the presence of C5-9 (membrane attack complex). However, hardly any C1q and C4 could be found in the ex vivo xenogeneic perfused hearts. Staining for factor B was positive and proved activation via the alternative pathway. Beyond that, the presence of properdin binding even indicated an upregulation of the alternative pathway C3 convertase.(ABSTRACT TRUNCATED AT 250 WORDS)

Xenogeneic ex vivo hemoperfusion of rhesus monkey livers with human blood

This model of completely isolated ex vivo hemoperfused RM livers reflects immunologic effects of donor organs and the humoral blood components of the recipient. The reaction between the isolated organ and recirculating blood allows us to concentrate on effects and products liberated under such a selected but limited situation. The slight influence of used materials on the monitored parameters in the circuit is of no importance. The massive release of TNF alpha, IL-1 beta, IL-6, IFN gamma, and 6kPGF1 alpha between 15 and 60 minutes after reperfusion was the specific result of xenoperfusion. IL-2 increases after 60 minutes. Soluble human IL-2R seems to be eliminated from the perfusate by the RM liver to about 50% of initial values. It increases again sharply beyond 180 minutes now originating from the RM liver. During the whole perfusion time, soluble HLA-I antigen and the detected adhesion molecules decrease to 50% of their initial values.

Bone formation in coralline hydroxyapatite. Effects of pore size studied in rabbits

We analyzed osseous reactions in the rabbit femoral condyle to coralline hydroxyapatite bone substitutes of various pore sizes by radiology and histology. The results were compared to bone repair of empty cavities and to integration of allografts. Spontaneous bone repair of the empty cavities took approximately 12 weeks, while integration of the cryopreserved allografts occurred after 9 weeks. However, no signs of new bone formation were found with the 200 microns pore size hydroxyapatite. In contrast, there was substantial production of bone within the 500 microns pore size implants at 12 and 26 weeks. Our results indicate that the pore size of the coralline hydroxyapatite influenced the development of bone in the implants in the cancellous bone bed of the rabbit femoral condyle. The results also show that spontaneous bone repair should be taken into consideration when the integration of implants is evaluated.

Engineering of cartilage tissue using bioresorbable polymer carriers in perfusion culture

Bioresorbable polymer fleeces with a high internal surface area were used as temporary matrices to establish three-dimensional cultures of isolated human articular chondrocytes. The polymer surface was coated with poly-L-lysine to support cell attachment. The resulting cell-polymer tissues were cultured in perfusion culture chambers to achieve a constant supply of nutrients by diffusion. Retention and accumulation of extracellular matrix components synthesized by the chondrocytes were improved by encapsulation of the cell-polymer integrate in agarose gel. The cell-polymer tissues formed abundant collagen fibrils in vitro with a typical cross-triation clearly visible in electron microscopy analysis. Chondrocytes and intercellular matrix stained positively with monoclonal antibodies specific for differentiated chondrocytes and type II collagen. Synthesis of proteoglycans and collagen was also evident by further analysis with alcian blue and azan staining of cell-polymer tissue sections. The presented experimental tissue culture technique offers a novel concept for the in vitro formation of vital cartilage implants for reconstructive surgery or treatment of destructive joint diseases and possibly for the in vitro engineering of human tissues in general, with applications in drug testing and replacement of animal experiments.

[Autoantibodies against cartilage components: clinical relevance for reconstructive surgery in the area of the head and neck]

The clinical relevance of antibodies against components of cartilage in the reconstructive surgery has not yet been clarified. In our study four groups of patients with successful and unsuccessful autologous cartilage transplantation in rhinosurgery, patients with ear perichondritis and patients with tracheal stenosis after long-term intubation were investigated for the presence of a humoral immune reactivity to cartilage. The control groups consisted of healthy persons and patients with RA. The antibodies against cartilage matrix and chondrocytes were determined using indirect immunofluorescence methods. Patients with unsuccessful cartilage transplantation showed increased antibodies against autologous cartilage (until 1:100) compared to the patients with successful cartilage transplantation. Furthermore, patients suffering from ear perichondritis and tracheal stenosis showed also increased antibodies against cartilage. These data suggest that a humoral immune reactivity against autologous cartilage--independent of an infection--can be one cause for the destruction of cartilaginous tissue.

Reduction of cyclosporine-induced nephrotoxicity by cilastatin following clinical heart transplantation

The objective of this prospective, randomized, placebo-controlled, single-blinded study in 28 heart-transplanted patients was to investigate whether the dehydropeptidase inhibitor cilastatin reduces cyclosporine-induced nephrotoxicity. Cilastatin is available only in combination with imipenem, a beta-lactam antibiotic to which it is added for reduction of nephrotoxic side-effects of the antimicrobial agent. Patients received either 100 ml placebo (n = 12) or 100 ml (500 mg) imipenem/cilastatin (n = 16) twice perioperatively, and 4 times daily for the first 7 postoperative days. Serum creatinine and urea, as well as urine concentrations of N-acetyl-beta-D-glucosaminidase, which is directly correlated with tubular cell damage, were used as markers for renal function. Thromboxane B2 and 6-keto-prostaglandin F1-alpha serum concentrations were determined to investigate whether there is an imbalance in synthesis of thromboxane A2 and prostacyclin as a possible mechanism for cyclosporine-induced nephrotoxicity. Two placebo patients and 6 patients receiving imipenem/cilastatin had to be excluded from further analysis. Three of 10 placebo patients required hemofiltration, and 2 of them even required hemodialysis, as compared with none in the imipenem/cilastatin group. Creatinine concentrations increased significantly from the second to the fourth postoperative day in the placebo group, but remained nearly normal in cilastatin patients (P < 0.05 for intergroup comparison on postoperative days 2-4). The same trend was observed in urea and N-acetyl-beta-D-glucosaminidase concentrations, without the difference reaching statistical significance. For thromboxane B2 and 6-keto-prostaglandin F1-alpha no differences between the groups could be found. These results suggest that imipenem/cilastatin can counteract acute cyclosporine-induced nephrotoxicity, which appears to be associated with alterations of tubular cell function. The combined use of cyclosporine and imipenem/cilastatin appears to be advantageous in patients following heart transplantation during the initial postoperative period.

Fundamental problems of xenotransplantation

Xenogeneic transplantation of organs will certainly solve the problem of organ shortage if it succeeds in long term function of the xenografts. Accommodation and rejection of the grafts depend however not only on the immunological mechanisms but, as already recognized in chronic rejection i.e. transplant atherosclerosis, in many other biochemical and physiological, even morphological characters including inflammatory events originating from infections. Preformed natural antibodies, an important part of the preimmunitary system turn again out to be a lock with seven seals. With increasing amounts of data the confusion about possibly an epiphenomenom in xenotransplantation becomes complete. Complement developed by nature before immunoglobulins can be activated by many ways--inducing a series of cascades like cell lysis, blood clotting, cell adherence and liberation of oxygen radicals. Large amounts of foreign proteins are released in the circulation when for example xenogeneic livers or other organs suffer from hyper acute rejection. The function of the liberated enzymes, hormones and inhibitors is far from being understood or even investigated. The amount of potassium released from a deteriorating liver is able to mimic a sometimes lethal cardioplegic situation. First data coming from intra vital microscopy herald that adhesion molecules, the newest but not last in line of trouble shooters play together with integrins and interleukins and eicosanoids a major role in microcirculation, be it as falsely activated system or as incompatible system not able to protect from the attack of white blood cells, their adhesion and migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperacute rejection in an ex vivo model of renal xenografting. Role of the mediator response and its pharmacologic manipulation by the specific platelet-activating factor antagonist WEB 2086BS

The pharmacologic modulation of the platelet-activating factor antagonist WEB 2086BS on the release of metabolites of the arachidonic acid and the cytokine TNF alpha was investigated in an ex vivo xenograft model of hyperacute rejection. Pig kidneys were perfused for 60 min in a perfusion system with oxygenated heparinized human or autologous porcine blood, respectively. During autologous perfusion, no alterations in the mediator response could be detected, whereas xenogeneic perfusion induced progressive release of mediators. Treatment by the platelet-activating factor antagonist WEB 2086BS resulted in a significantly reduced liberation of the cytokine TNF alpha and of prostanoids. The histological findings verified that a hyperacute rejection in the xenogeneic perfused organs had occurred, which was mitigated by the treatment with WEB 2086BS. This observation confirms that inflammatory mediators play a decisive role in hyperacute xenogeneic rejection. The results suggest that suppression or manipulation of mediator-specific tissue receptors by receptor-antagonists could be an additional therapeutic mode to control hyperacute rejection in xenogeneic transplantation.

Intragraft events after heart transplantation: an experimental study comparing cytology in coronary sinus blood, peripheral blood, and daily histology

Acute rejection is a frequent consequence after heart transplantation. To expand our knowledge of the rejection process and to investigate some intragraft events during acute rejection, the following experimental transplantation model was designed. Right cervical heart transplantation was performed in 12 mongrel dogs. Two experimental groups of six animals each received different immunosuppressive regimens. All animals were treated with daily triple drug therapy. In contrast to group 1, the animals in group 2 received high-dose steroids during rejection. The condition of the hearts was examined by daily transmural biopsies, graded according to the Billingham classification. To detect and quantify alterations in the mononuclear cell subsets of the myocardial venous return, blood samples from the coronary sinus blood (CS) and from peripheral blood (PB) were taken simultaneously with the biopsy. The total number of lymphoblasts and activated lymphocytes was determined and an activation index (AI) was calculated. The data referred to was established from 337 transmural biopsies. The AI of PB (n = 287) correlated well with the different stages of acute rejection (grade B0: AI = 2.2 +/- 2.1; grade B1 + 2: AI = 6.3 +/- 1.7; grade B3: AI = 10.0 +/- 4.7; P < 0.001). The rejection kinetics of both groups, including the rejection-free interval following high-dose steroid administration in group 2, could be expressed accurately by the AI. The time course of the total number of lymphoblasts in CS versus PB demonstrated that the lymphoproliferative response started 4 days prior to the first intramyocardial signs of rejection (mean = 3.8 +/- 0.7; n = 12).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen presenting cell function of class II positive human nasal chondrocytes

It is postulated that class II positive chondrocytes may be actively involved in the destruction or rejection of vital transplanted cartilage grafts. To investigate whether human nasal chondrocytes may also function as accessory cells in ongoing immune reactions with cartilage destruction, mixed leukocyte-chondrocyte cultures and antigen presentation assays were performed. Freshly isolated HLA class II antigen negative chondrocytes obtained from nasal septa were not stimulatory to autologous resting T lymphocytes. HLA class II positive chondrocytes treated with gamma-interferon were able to present antigens to autologous activated T cells derived from an antigen (tetanus) specific T cell line. Upon incubation with activated T cells, initially class II negative changed their phenotype resulting in the expression of class II antigens and enabling them to effectively present antigen. These results suggest an active role of chondrocytes in the rejection of cartilage grafts.

Expression of ICAM-1 on isolated human nasal, auricular and costal chondrocytes

Expression of intercellular adhesion molecule-1 (ICAM-1) on targets has been reported to be a relevant factor for leukocyte migration, adhesion and function. Because stimulated chondrocytes have been shown to express molecules of immunological import (like HLA class II antigens) and because rejected or resorbed cartilage grafts used in the field of ENT are often characterized by adjacent infiltrating leukocytes, the presence of ICAM-1 on human nasal, auricular and costal cartilage was investigated. For this study, cartilage tissue sections and chondrocytes in suspension as well as cultured chondrocytes were prepared. Specific monoclonal antibodies (mAb) were used for immunocyto- and immunohistochemical Alkaline-Phosphatase-anti-Alkaline-Phosphatase staining (APAAP staining) as well as for flow cytometry analysis. ICAM-1 on healthy cartilage tissue sections was not found. On the other hand, both chondrocytes freed from matrix and cultured chondrocytes showed strongly positive staining patterns for ICAM-1. This result was obtained for chondrocytes from nasal, auricular as well as costal cartilage. This observed expression of ICAM-1 on chondrocytes with defective extracellular matrix demonstrates that cartilage cells are able to synthesize ICAM-1 without any paracrine stimulus from non-chondrocyte cells. It suggests that ICAM-1 plays a role in processes where tissue damage leads to the exposure of chondrocyte surfaces. Therefore, ICAM-1 expression on chondrocytes may also be a factor in destructive cartilage graft resorption.

The contribution of endothelial cells to hyperacute rejection in xenogeneic perfused working hearts

The mechanisms leading to the hyperacute rejection of a vascularized xenograft are still incompletely understood. The first stage of the rejection process is when blood of the recipient comes into contact with the endothelium of the xenograft. A working heart model was used to examine endothelium-related processes and their impact on organ function. Pig hearts were perfused with porcine (autologous) or human (xenogeneic) blood. Cardiac function was evaluated by calculating the stroke work index, arteriovenous oxygen, coronary flow, and resistance. PgF1a as a marker of endothelial activation, its antagonist TXB2, and myoglobin reflecting myocardial damage were measured in the hemoperfusate. H&E and PAS staining and immunohistological demonstration of factor VIII-related antigen was performed. Xenogeneic perfused porcine hearts showed significantly less stroke work, a higher arteriovenous oxygen difference, and an increased coronary resistance. Factor VIII-related antigen could not be demonstrated immunohistologically on the endothelium after xenogeneic perfusion. PgF1a levels were significantly higher in the xenogeneic hemoperfusate, indicating endothelial cell activation. The concentration of myoglobin in the hemoperfusate remained within normal values and was similar during autologous and xenogeneic perfusion. Therefore endothelium-related processes are likely to affect the coronary circulation--thus being one mechanism leading to diminished cardiac performance during hyperacute rejection.

Cytoimmunological monitoring after homograft valve replacement

Examination results concerning immunological reactions in cryopreserved allograft valves during the early postoperative course are so far not available. Cytoimmunological monitoring (CIM) is a well established method to prove rejection reaction after allograft transplantation and was used in this study. Allograft valves were harvested from patients who underwent heart transplantation, and did not require sterilizing in antibiotic solutions. The valves were dissected, conserved and subsequently frozen to -40 degrees C and stored in a freezing system at -196 degrees C. During the first 3 weeks following allograft implantation, CIM was performed daily. An activation index (AI) was determined from the cytological evaluation of the mononuclear concentrate in the peripheral blood. An increase of the AI > 1 was defined as an immunological reaction. As control we performed 98 CIM examinations in eight patients who underwent bioprosthetic valve replacement in the aortic position. Echocardiography (TTE and TEE) was used postoperatively as function control. Out of 16 patients who underwent cryopreserved aortic valve implantation in the aortic position, 336 CIM-results were obtained. An immunological reaction could be detected in all patients, starting on the 5th day on average. Comparing ABO-compatible (group I, n = 9) with ABO-incompatible (group II, n = 7) allografts, the AI-maximum in group I was 1.4 with a mean duration of 1.5 days. Group II was characterized by more intensive immunoreactions (mean = 2.3) which proved to be even more prolonged (mean = 3.3 days, P < 0.05). Nevertheless it became apparent that all observed immunological events were completely reversible without the need for immunosuppressive drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

[Cartilage-specific autoimmunity in otosclerosis]

The otic capsule of patients with otosclerosis contains premature bone with numerous cartilaginous remnants. Some investigators have proposed that the pathogenesis of otosclerosis is related to these cartilaginous rests in the otic capsule. In this study we investigated the presence of a humoral immune reaction against cartilage-specific antigens using ELISA-methods in patients with otosclerosis. Concomitantly, 8 age- and sex-matched healthy blood donors, free of any symptoms of autoimmune disease, served as controls. The following antigen substrates were used: collagen (I, II, III, VI, IX and XI), chondrocytes and chondrocyte membranes. Findings then showed that the levels of antibodies to collagens type II and IX as well as to chondrocytes were higher in the otosclerosis patients than in the control subjects. The high titer of antibodies against chondrocytes was not accompanied by an increase in antibodies against the chondrocyte membranes. To our knowledge these observations represent the first evidence for the existence of autoantibodies against minor collagens and chondrocyte-specific antigens and support a possible role for a cartilage-specific autoimmunity in the etiopathogenesis of otosclerosis.

Synthesis of human cartilage using organotypic cell culture

The limited supply of fresh autologous cartilage tissue for use in reconstructive surgery necessitates the use of vital banked allografts. A feasible in vitro production of cartilage tissue composed of living cells requires the use of modern tissue culture techniques retaining the phenotypic characteristics of chondrocytes. With this purpose in mind, human chondrocytes were isolated and cultured using different culture procedures: monolayer, suspension and agar gel. The differentiation state of chondrocytes as well as proteoglycan and collagen syntheses were assessed by histochemical and immunohistochemical methods. Whereas chondrocytes in monolayer displayed an unstable phenotype and tended to dedifferentiate, in three-dimensional culture the chondrocytes remained morphologically, phenotypically and functionally differentiated. Furthermore, an accumulation of matrix products pericellularly was observed in the agar gel. The results suggest that three-dimensional cultures in agar gel may allow the in vitro production of bioartificial cartilage for transplantation.

[In vitro studies of possible transmission of human immunodeficiency virus (HIV) by allogeneic cartilage transplants]

With the increasing prevalence of the human immunodeficiency virus (HIV), the possibility of a transmission of HIV via allogenic transplants has increased. To assess the risk of transferring HIV with allogenic cartilage grafts we investigated the susceptibility of chondrocytes to the virus. Our results indicate the absence of the HIV receptor (CD-4-molecule) on chondrocytes by immunohistochemistry and FACS analyses. Furthermore cultures from chondrocytes and high doses of HIV-1 did not show an active replication. Hence, we conclude that normal cartilage cells cannot be infected by HIV. This means that the risk of HIV transmission by cartilage allografts is very low if no contaminating tissues like blood, perichondrium and calcifications etc. are present.

Effects of therapeutic ribose levels on human lymphocyte proliferation in vitro

Ribose has been used successfully in the treatment of ischemic heart disease and muscular enzyme deficiencies, and its administration also facilitates the diagnosis of coronary artery disease by influencing thallium-201 scintigraphy. Concerns about the safety of ribose therapy have been triggered by reports about inhibitory effects of ribose on cell proliferation in vitro. This study examines possible side effects of ribose on human lymphocytes. Unstimulated and mitogen-stimulated human lymphocytes were incubated with ribose concentrations associated with high-dose oral administration, i.e., 3.5 mM, and with two- (7 mM) and tenfold (35 mM) higher concentrations. Cell cultures with matching glucose concentrations served as controls. Incorporation of [3H]thymidine into cells was used to measure cell proliferation. No significant inhibition of human lymphocyte proliferation in vitro was observed in mitogen-stimulated cells. Unstimulated cultures showed significant inhibition only at 35 mM ribose. It is concluded that ribose plasma levels associated with high-dose oral administration do not inhibit human lymphocyte proliferation in vitro. No evidence was found that short-term ribose therapy is harmful to human lymphocytes.

[Fundamental concepts in the implementation of the spectroscopic magnetic resonance for the determination of the biological quality of human cartilage transplants]

Cartilage grafts are often used in reconstructive surgery for compensating loss or defect in tissues. Future progress in this field are related to the resolution of some problems concerning the preservation in our tissue-banks. Several time-expensive biochemical, histological and autoradiographic methods have been employed in the past to describe the metabolic properties and pathological changes of preserved and transplanted cartilage grafts. In this article we show that magnetic resonance spectroscopy offers the possibility to recognize metabolic changes in cartilage tissues as a consequence of storage conditions: anaerobic metabolism (lactacte) and lysis of collagenic structures of the matrix. In this way objective parameters assessing the biologic quality of grafts can be obtained without any destructive impact on the specimen.

Xenotransplantation: state of the art

Today, at the beginning of the xenogeneic era of transplantation, only simple and single observations about comparative physiology and biochemistry, and even anatomy, are known. Very few data exist which in addition inform about mechanisms after successful xenotransplantation. Nothing is known about phenomena following successfully suppressed hyperacute xenogeneic rejection. Neither the elimination of single factors nor the mitigation of whole systems have led to clinically relevant survival times. Pig organs transplanted into nonhuman primates survived a maximum of 22 days. The hope that transgenic manipulation and modification would be useful to prolong survival times of xenogeneic grafts still waits for evidence. But, within a short time, xenotransplantation could enable patients to receive a life-saving animal organ as an alternative to an allograft. Xenotransplantation would, as a new dimension in medicine, shorten if not eliminate waiting lists. Therefore, scientists must vigorously develop xenografting as a viable alternative for transplantation.

Ethical aspects in xenotransplantation

Ethics aims to achieve optimal human behavior. However, applied ethics depend on the cultural environment. In medicine, ethics could allow an amoral operation in a fetus or in chronically ill patients because it is new and rich in prospects for acquiring knowledge and could improve the quality of life of the patient or at least save the life. The operation itself must not be ill natured or unethical and the patient must not be misled or given false hope over the outcome. Ethics would allow us to offend the dignity of man, such as by xenotransplantation, because the wish for well being is often greater than the desire to retain dignity. Ethics in xenotransplantation must be based on the interests of the poor and unlucky patient and must aim for the good of everyone, but especially meet the patient's demands.

Human immunodeficiency virus cannot productively infect freshly cultured human cartilage cells

The use of cartilage allografts is being discussed because of the possible transmission of the human immunodeficiency virus (HIV). To further delineate the possibility for an HIV infection of cartilage cells the susceptibility and permissivity of normal human chondrocytes to HIV-1 was assessed in culture. Isolated cartilage cells were incubated during 30 days with the HIV, testing the production of viral p24 antigens and the formation of particle-bound reverse transcriptase (RT) in the supernatant. The H9 cell line was used as positive control. The production of p24 antigen did not occur on chondrocytes during the whole culture time. Furthermore, no RT activity was detected throughout the entire experimental period. Our results indicate clearly that HIV was not able to infect cartilage cells under these in vitro conditions, and, conclusively, HIV infection of cartilage in vivo is improbable.

[Comparative study of the effect of different chemical procedures on the antigenicity of allogenic transplants of the human trachea]

Replacement of long tracheal segments poses some unsolved problems, specially the undisponibility of an adequated substitution material. This study deals with some of the immunological aspects of the transplantation and preservation of human tracheal grafts. Since immunological rejection occurs in the first place as a consequence of incompatibility for class II antigens (HLA-DR, -DP and -DQ), their presence and distribution was studied using monoclonal antibodies and the immunoperoxidase method. Class II expressing cells were recognized in the mucosa and the mixed glandular tissue. Furthermore we investigated the influence of different preservation methods on the antigenicity of tracheal allografts. The results showed a total destruction of these antigens. We can conclude that chemically preserved human tracheal allografts are immunologically suitable for reconstructive surgery of the trachea.

A critical analysis of human immunodeficiency virus transmission using human cartilage allografts

Allogeneic cartilage represents an important source of tissue for reconstructive surgery in the head and neck. The use of allografts is now being discussed because of the possible transmission of the human immunodeficiency virus (HIV). The receptor for HIV in most cell types is the CD-4 molecule. Since cartilage is a popular homograft source, the purpose of this study was to investigate the presence of CD-4 molecules on cartilage tissue as detected with an immunoperoxidase staining and immunofluorescence flow cytometric analysis using a monoclonal antibody. Our results indicate clearly the absence of the HIV receptor on human cartilage tissue. We have concluded therefore that normal cartilage tissue cannot be infected by HIV, at least not through a CD-4-dependent mechanism.

[Cartilage transplantation in the area of the head-neck: comparative study of HLA class II antigen induction to chondrocytes in various culture systems]

Autologous and homologous cartilage grafts are often used in reconstructive head and neck surgery. Unfortunately, sometimes the outcome of such operations is endangered by graft rejection or resorption. Among other reasons, immunological reactions with HLA class II antigen expression are thought to be involved at least in failures of vitally grafted cartilage. Up to now, only one case of class II antigen expression in a cartilage graft "in vivo" has been reported. Nevertheless, it has already been demonstrated that stimulated cartilage cells are able to express "in vitro" class II antigens if grown in monolayer cultures. However, it has also repeatedly been shown that chondrocytes reveal strong dedifferentiating features if cultured in monolayers. Therefore, it was the aim of this study to examine whether isolated and stimulated chondrocytes also express class II antigens if cultured under in vitro conditions closer to the relevant in vivo situation. Hence monolayer, suspension, agar, alginate and organ cultures were prepared simultaneously and kept for up to 60 days. Chondrocytes were stimulated by the addition of IFN-gamma and tested for class II antigens. For the detection of the antigens immunocyto- and immunohistochemical APAAP stainings as well as flow cytometric measurements were made. In all examined culture systems a class II antigen induction could be observed. Any significant differences between the various cultures as to the intensity of antigen expression could not be detected. Consequently, the expression of class II antigens on stimulated human chondrocytes seems not to be a specificity of monolayer cultures. Therefore, class II antigen induction may be considered to play a role in the rejection/resorption of vitally grafted cartilage in reconstructive surgery.

A new device for the measurement of the arterial compliance using implantable sensors. Description and first experimental application

To determine the compliance of experimental arterial grafts and its chronic adaptation after implantation, a new device for measurements was developed which is combined with implantable sensors. The system is based on the physical induction phenomenon. Each sensor comprises two small coils of copper wire which are sutured opposite to each other to the arterial vessel. Up to 3 sensors are adapted to one electrical connector which can be covered subcutaneously. The device is able to read pulsatile diameter excursions of arterial vessels down to 0.02 mm. It was applied first to evaluate the elastic properties of a 4-mm dialdehyde-starch-preserved bovine internal mammary artery implanted in the canine femoral artery position. For comparison an ePTFE graft was used. At implantation the compliance of the biograft was calculated to be 0.028 +/- 0.009% mm Hg-1, which was half of the compliance of the native femoral artery (0.06 +/- 0.0025% mm Hg-1), but superior if compared to the PTFE (0.008 +/- 0.005% mm Hg-1). Within 6 months the compliance of the femoral artery decreased to 0.039 +/- 0.013% mm Hg-1, which was well matched now to the compliance of the biograft (0.027 +/- 0.005% mm Hg-1).

Evolutionary and immunological aspects of xenotransplantation

Immunological aspects in xenotransplantation are directly linked to evolutionary aspects. The immunological network with its high antigen specificity and species-specific interactions was developed to fight against the host's outside world including xenografts. The tremendous amount of reaction and mechanisms triggered by the performed natural antibody-endothelial cell reaction clearly indicates that only basic changes might overcome these problems. Even the introduction of transgenic donors might not be sufficient to modify more than one parameter, for example, complement activity. Total depletion of preformed natural antibodies is not compatible with normal life and the regulation of hormones and enzymes under xenogeneic conditions has just been discovered. Cellular mechanisms depend, as far as we know, on the delicate system of receptors, interleukins, and MHC antigens. From today's very early results we know that major changes exist already between closely related species. The investigation of xenogenic mechanisms has opened a totally new field of immunological interactions. Up to now there are no signs of solution to bridge clinically relevant times with xenogenic organs from widely divergent suitable donors with promising quality of life.

[Immunologic behavior of human tracheal transplants]

In this study we tried to investigate the antigenicity of human tracheal allografts. We found transplantation antigens in the mucosa and the mixed glands using monoclonal antibodies in an indirect immunoperoxidase method. However these antigens were able to be destroyed with a chemical preservation procedure. The diminution of the antigenicity could be also achieved in a tracheal transplant human recipient. These results show that the preserved trachea may be immunologically a suitable material for reconstruction in surgery of the trachea.

Bridging to transplant: allogeneic heart transplantation after xenografting

Xenografting seems to be a solution to use to bridge time intervals when desperately needed allograft cannot be obtained. A following allograft was never ventured. Nine dogs (weight, 20 to 25 kg; age, 2 years) underwent right cervical heart transplantation. Donors were silver foxes (3 to 4 kg). The animals were treated by triple-drug therapy consisting of cyclosporine, methylprednisolone, and azathioprine in clinical dosages. For control, six recipients received only allogeneic hearts and the identical immunosuppression. After rejection of the xenograft, a second allogeneic heart was anastomosed subsequently to the same right cervical vessels. Routine histologic and immunohistologic examinations were performed. Thromboxane B2 and 6-keto-prostaglandin F1 alpha were determined daily in peripheral blood. After final rejection the sensitization of the recipient was controlled by hemagglutination test. Survival time of the xenografts was 9.6 +/- 1.2 days; the subsequent allogeneic hearts under the same therapy beat for 4.5 +/- 5.0 days. The average survival time of control hearts was 18 +/- 1.9 days. The five hyperacute second allografts showed signs of humoral rejection by absence of inflammation. The release of thromboxane B2 was different in hyperacute, accelerated, or cellular rejection. In contrast to the long-functioning grafts, thromboxane B2 persisted during hyperacute rejection at a high level. However, 6-keto-prostaglandin F1 alpha showed no significant differences between longtime survivors and hyperacute rejecting hearts. After xenogeneic transplantation, all recipients showed hemagglutinating titers between 1:4 and 1:16. Allogeneic grafts have a different kinetics of rejection after xenogeneic heart transplantation compared with control hearts. Thromboxane B2 seems to be an important mediator in hyperacute rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneity of alveolar macrophages in experimental silicosis

The alveolar macrophage (AM) population has been shown to be heterogeneous in composition as well as in function. The aim of our study was to assess morphological and functional features of AM in an experimental model of quartz-induced lung fibrosis by flow cytometric methods. Twelve cynomolgus monkeys were exposed 8 hr/day, 5 days/week for 26 months to either normal atmosphere (n = 5) or 5 mg/m3 DQ12 less than 5 microns quartz dust (n = 7). After 20 months of exposure, we studied AM phagocytosis by incubating bronchoalveolar lavage cells with fluorescent polystyrene microspheres (mean diameter 1.91 microns). Using a fluorescence-activated cell sorter analyzer, AM subpopulations were identified via their volume/side scatter properties. After selective electronic "gating" of the AM populations, both the percentage of phagocytic AM and the mean number of ingested microspheres per AM were determined. In addition, a phagocytic index (microspheres/AM x % phagocytic AM x 10(-2) and a hypothetical total phagocytic capacity of one lung (phagocytic index x total number of AM x 10(-6) were calculated. The total bronchoalveolar lavage cell counts rose (75.6 +/- 11.3 x 10(6) versus 10.1 +/- 0.8 x 10(6)) significantly after quartz exposure. In contrast, the percentage of phagocytic AM was significantly (p less than 0.05) reduced (43.5 +/- 5.0% versus 74.2 +/- 1.4%). Flow cytometric measurements revealed the appearance of an AM subpopulation characterized by size/granularity features identical to blood monocytes. Only minimal numbers of these cells were found under normal conditions, but they constituted 50% of the entire AM population in the quartz group.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental evaluation of the dialdehyde starch preserved bovine internal mammary artery as a small diameter arterial substitute

A canine femoral artery model was used for evaluation of a dialdehyde starch preserved bovine internal mammary artery (BIMA) (3 and 4 mm internal diameter) in comparison to a polytetrafluoroethylene (PTFE) graft. The study comprised three groups for a 2-hour (n = 7, 3 mm), 3-month (n = 10, 4 mm), and 6-month (n = 10, 4 mm) follow-up. The thrombogenicity of the grafts was measured after 2 hours and 3 months using chromium 51 labeled autologous platelets. In addition, compliance studies were done. To control the wall stability of the xenografts, the collagen content before implantation and after explantation was examined together with the diameter of the grafts. Healing characteristics were studied using appropriate histologic methods. The acute platelet adhesion rate (2 hours) of the BIMA graft was 181 +/- 69 x 10(4) platelets/mm2 as compared to 57 +/- 43 x 10(4) for PTFE (p less than 0.05, t-test). However, after 3 months the thrombogenicity of the biograft had decreased whereas the platelet count at the PTFE graft had increased (BIMA: 79 +/- 48 x 10(4); PTFE: 179 +/- 102 x 10(4), p less than 0.05). At implantation, the compliance of the BIMA graft was 0.028% +/- 0.009% per mmHg as compared to 0.06% +/- 0.0025% of the femoral artery. The PTFE graft was uncompliant (0.008 +/- 0.005). After 6 months, the compliance of the femoral artery had decreased to 0.039% +/- 0.013% per mmHg, which was now well matched to the nearly unchanged compliance of the biograft (0.0027 +/- 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)