Infectious Disease Transmission through Cell, Tissue, and Organ Transplantation: Reducing the Risk through Donor Selection

Human skin processing affects clinical outcome in allograft recipients

Skin allografts represent a milestone in burn patient treatment. However, skin procurement is still burdened by high rates of contamination, and validation procedures have not yet been standardized. In addition, it is not clear if tissue viability affects allograft skin outcomes. In 2120 skin samples from 610 donors, a retrospective analysis was performed to identify donor and procurement variables associated with bacterial contamination and tissue viability. Post-processing contamination was associated significantly with the donor type, cause of death, length of hospitalization, procurement site, surgeon, interval between procurement and banking, and decontamination method. Tissue viability appeared to be negatively associated with freezing. In two series of skin allograft recipients (155 and 195 patients), we evaluated the role of skin characteristics and procurement variables on clinical outcomes. We found that the length of hospitalization was associated significantly with donor age. Procalcitonin and PCR values in allograft recipients were correlated with the decontamination method. No significant associations were observed between tissue viability and clinical outcomes (length of hospitalization, cause of donor death, or inflammatory parameters) after allograft transplantation. In these large case series, we identified donor and procurement variables that may affect allograft skin recipients. The decontamination method appeared to be a critical step for skin allograft requiring better standardization.

Re-assessing the risk of undetected HBV, HCV and HIV in deceased tissue and living surgical bone donors in England

Testing of living surgical bone and deceased tissue donors by NHS Blood and Transplant (NHSBT) has included individual donation (ID) nucleic acid testing (NAT) for HBV, HCV and HIV since 2008. Here, the well-established window period methodology was used to estimate residual risk (RR). Prevalence of viral markers was calculated among both tissue donor populations. Incidence was derived by adjusting incidence among new blood donors by the prevalence ratio for tissue and new blood donors. Residual risk (RR) was calculated as the product of incidence and duration of WP for single donor HBV NAT at 0.058 years (21 days), HCV NAT at 0.008 years (3 days) and HIV NAT at 0.014 (5 days). Between 2013 and 2017, 7886 living surgical bone donors were tested, 16 were positive for markers of HBV, HCV and HIV. HCV had the highest prevalence at 114/100,000 donors. Incidence and RR was highest for HBV at 3.55/100,000-person years and 0.32/100,000 donors (95% CI 0.11/100,000-1.42/100,000). Among 9751 deceased tissue donors tested, 22 were positive for viral markers. HBV had highest prevalence at 174/100,000 donors, and the highest incidence and RR at 8.12/100,000 person years and 0.74/100,000 donors (95% CI 0.08/100,000-2.99/100,000). Using ID NAT, RR of not detecting a HBV, HCV and HIV WP donation among tissue donors is less than 1/100,000 donors. These estimates provide a good starting point for discussing potential risks of viral transmission through tissue transplant with patients.

Seropositivity of blood samples of 31,355 cornea donors from a tertiary care network of eye banks

PURPOSE

To evaluate the seropositivity of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and syphilis from blood samples of cornea donors and assess correlation between seropositivity for HIV and syphilis.

METHODS

Retrospective analysis of blood samples of 31,355 cornea donors for HIV, HBV, HCV, and syphilis was performed. Postmortem blood samples were analyzed by a rapid screening test for anti-HIV envelope antibodies against HIV 1 and 2, HBV surface antigen, antibody to HCV and anti-cardiolipin antibodies for syphilis by rapid plasma reagin test.

RESULTS

The overall seropositivity rate was 4.28% (1343/31,355 donors). All positive donors were reactive for a single serological test. The seropositivity rate for HIV was 0.93% (95% CI 0.83-1.04%), for HBsAg was 1.56% (95% CI 1.43-1.7%), for HCV was 1.19% (95% CI 1.08-1.33%) and for syphilis was 0.59% (95% CI 0.52-0.69%). The trends in seropositivity rates showed a decline for three viral markers: HIV (2010, 1.17% to 2018, 0.72%, p = 0.02), HBsAg (2010, 1.98% to 2018, 1.05%, p = 0.0006) and HCV (2010, 1.32% to 2018, 0.43%, p < 0.0001). The seropositivity rates for syphilis showed a progressive increase when compared to baseline (2010, 0.14% to 2018, 1.14%, p < 0.0001). There was no relationship between seropositivity for HIV and syphilis (p = 0.18).

CONCLUSIONS

The overall seropositivity for HIV, HBV, HCV and syphilis was 4.28%. Seropositivity was highest for HBV. The study did not find correlation between seropositivity of HIV and syphilis.

The Causes for the Loss of Cellular Material at the Qualification Stage and the Influence of the Patient's Flora on Culture Infection

There are several causes leading to the loss of cellular material earmarked for transplantation. This paper aims to evaluate the number of lost donors and lost cells in the culture by means of verifying both the results of the qualification tests and the presence of microorganisms in the cellular material. The analysis involved 86 donors hospitalized for thermal burns, from whom cells were harvested for keratinocyte and fibroblast cultures in the years 2011 to 2015. All potential donors underwent qualification tests: Anti-HIV-1,2; HBsAg; Anti-HCV-Ab; HBc, and a specific test for syphilis. In the case of skin fragments collected for culturing, the microbiological tests included the carrying fluid, the medium after 1 change, and the medium during culturing and before transplantation. Skin donors for cell cultures were assigned to the groups based on if the skin was collected up to 7 days following the burn or later. On average, 12% of the disqualifications were reported among donors for cell culturing. The most frequent cause of donor disqualification (54% of all disqualifications) was a positive HBc(+). The occurrence of fungal infections detected in the cellular material was over 30%. Establishing the culture after day 7 following the injury immediately increases the risk of infection by 25% in comparison to those cultures established before or on day 7 following the injury. Proper disinfection of donor place is crucial, but sometimes insufficient for maintenance sterility in cell culture. The risk of infection increases 25% after 7 following the injury.

Treatments for enhancing the biocompatibility of titanium implants

Titanium surface treatment is a crucial process for achieving sufficient osseointegration of an implant into the bone. If the implant does not heal sufficiently, serious complications may occur, e.g. infection, inflammation, aseptic loosening of the implant, or the stress-shielding effect, as a result of which the implant may need to be reoperated. After a titanium graft has been implanted, several interactions are crucial in order to create a strong bone-implant connection. It is essential that cells adhere to the surface of the implant. Surface roughness has a significant influence on cell adhesion, and also on improving and accelerating osseointegration. Other highly important factors are biocompatibility and resistance to bacterial contamination. Bio-inertness of titanium is ensured by the protective film of titanium oxides that forms spontaneously on its surface. This film prevents the penetration of metal compounds, and it is well-adhesive for calcium and phosphate ions, which are necessary for the formation of the mineralized bone structure. Since the presence of the film alone is not sufficient for the biocompatibility of titanium, a suitable surface finish is required to create a firm bone-implant connection. In this review, we explain and compare the most widely-used methods for modulating the surface roughness of titanium implants in order to enhance cell adhesion on the surface of the implant, e.g. plasma spraying, sandblasting, acid etching, laser treatment, sol-gel etc., The methods are divided into three overlapping groups, according to the type of modification.

Detection and quantification of human immunodeficiency virus and hepatitis C virus in cadaveric tissue donors using different molecular tests

BACKGROUND

Tissues from cadaveric donors are used in several clinical circumstances, and the transmission of infectious diseases has been reported. Cadaveric donor (CD) blood sample analysis is challenging due to its poor quality. However, studies have demonstrated the usefulness of molecular based methods, and the lack of studies using available commercial molecular tests was reported.

OBJECTIVE

The aim of this study was to evaluate the performance, specificity, sensitivity, and accuracy of different commercial molecular tests for HIV and HCV detection and quantification in CD through spiked samples.

STUDY DESIGN

20 CD and 20 blood donor samples were tested using 1,000 copies/mL and 1,000 IU/mL of lyophilized standards of HIV and HCV, respectively. Samples were analyzed by different molecular kits: XPERT HCV Viral Load and HIV-1 (Cepheid), COBAS® TaqMan® HIV-1 and COBAS® TaqMan® HCV Test, v2.0 (Roche), and artus® HI Virus-1 QS-RGQ and artus® HCV RG RT-PCR Kit (Qiagen).

RESULTS

HIV and HCV in CD were detected by RT-PCR-based quantitative kits. The tests performed by the Cepheid and the Roche kits showed the most accurate, sensitive and specific results, however, a wide variability between the assays and kits was observed. The Qiagen kits did not demonstrate satisfactory results.

CONCLUSIONS

CD evaluation showed great variability. The Cepheid and Roche kits were more sensitive for detecting HIV on CD and Cepheid was the most efficient kit for HCV quantification in CD. The Roche and Cepheid kits can be used to screen tissue donors for HIV and HCV.

Validation of Spiked Postmortem Blood Samples from Cornea Donors on the Abbott ARCHITECT and m2000 Systems for Viral Infections

Background

Transplantation of human corneal tissue is associated with the potential risk of transmittance of viral infections. In accordance with European directives and federal laws, in Germany each tissue donor has to be tested for infectious diseases such as hepatitis B and C virus (HBV and HCV) and human immunodeficiency virus (HIV) infection. However, most of the currently available CE-marked serologic and nucleic acid screening systems are only validated for antemortem blood.

Methods

Twenty related and paired ante- and postmortem blood samples from cornea donors were obtained and subsequently analyzed for hepatitis B surface antigen (HBsAg), hepatitis B antibody (anti-HBc), anti-HCV, HCV RNA, anti-HIV-1/2, and HIV p24 Ag using Abbott test systems. The sera were also spiked with reference materials in concentrations giving low and high positivity for HBV, HCV, and HIV markers.

Results

The spiked ante- and postmortem sera from related donors showed similar results for HBsAg, anti-HBc, anti-HCV, HCV RNA, anti-HIV, and HIV p24 Ag, indicating a high stability of viral markers in cadaveric specimens. Three cornea donors had a medical history of HBV infection and revealed anti-HBc at similar levels in the ante- and postmortem sera. In addition, there was a single postmortem sample demonstrating a weak signal of anti-HIV-1 and HIV-1 p24 Ag. False-positive or false-negative results were not detected. The results obtained with the Abbott ARCHITECT analyzer and Abbott RealTime HCV PCR showed no significant differences.

Conclusion

The analyzed screening assays are suitable for the detection of infectious markers of HBV, HCV, and HIV at similar levels in spiked ante- and postmortem sera from cornea donors.

Fresh Frozen Allogeneic Bone Block in Maxillary Sinus Floor Elevation: Histomorphometric Analysis of a Bone Specimen Retrieved 15 Years after Grafting Procedure

Nowadays implant-prosthetic rehabilitations are one of the best solutions for rehabilitating our patients. These allow obtaining rehabilitations with optimal functional and aesthetic performances. Often patients, who undergo implant-prosthetic therapy, have the conditions of edentulias, single or multiple, that have been going on for some time. This, according to the literature, produces resorption of the alveolar bone, a process that is complicated in the posterior area of the upper arch by a pneumatization of the maxillary sinuses. The loss of vertical height, so that the implant fixtures can be inserted, requires a maneuver called maxillary sinus floor elevation. This procedure, now safely performed with piezoelectric instruments, allows increasing bone height through bone grafting. In this study, the tissue obtained from a patient, after 15 years from the intervention, was evaluated by histological and SEM analyses. The bone healing in the patient has led to a perfect integration between the patient’s bone and the fresh frozen allograft used, however still present and detectable after 15 years.

Effect of x-rays and gamma radiations on the bone mechanical properties: literature review

The bone auto grafting, isografting, allografting and xenografting are used for defective bone replacement or treatment in almost all living species. The X-ray and Gamma (electromagnetic radiation) sterilization performed on the donor bone graft to prevent toxicity or migration of virus/bacterial infections from donors to reciver. Conversely, X-ray and Gamma radiation deteriorates the bone mechanical properties and bone become more susceptible to fracture. Fracture toughness as well as other mechanical properties of bone change with these radiations. In this literature review the effect of the X-rays and Gamma radiation on bone mechanical properties are discussed. All relevant literature was reviewed. After reviewing the literature only the research relating to the effect of X-rays and Gamma radiations on bone mechanical properties are included. Literature studies showed significant effect of the X-rays and Gamma radiations on the mechanical properties of the bones. In some studies the differences exists on the doses of radiations which were discussed in this study. The high energetic electromagnetic radiation (X-rays and Gamma radiations) changed/modify the collagen network of the bone, which reduced the mechanical properties of bone; however these changes depend on the radiation dose.

Rabies virus transmission via solid organs or tissue allotransplantation

BACKGROUND

Rabies, for which the mortality rate is almost 100%, is a zoonotic viral disease that can be transmitted via solid organs or tissue allotransplantation. Dozens of deaths from rabies via solid organs or tissues allotransplantation (ROTA) have been documented during the last decades. In 2015 and 2016, two cases of rabies virus transmission via solid organs or tissue allotransplantation were reported in China, which further underscore the risk and importance of this special type of rabies for organ transplant recipients.

MAIN TEXT

From 1978 to 2017, at least 13 cases of ROTA, causing dozens of deaths, have been reported worldwide, whether in the high-risk or low-risk countries of rabies. The reported incubation period of ROTA ranges from 11 days to more than 17 months, while the historical incubation period of rabies is generally considered to range from ~ 1 week to several years. The pathogenesis of ROTA is not clear, but the use of post-exposure prophylaxis (PEP) can play a protective role in the transplant recipients. We also summarize reports about ROTA in China, combined with the actual situation regarding work on rabies surveillance and elimination, and suggest countermeasures for the prevention and control of ROTA in the future.

CONCLUSIONS

Understanding the significance of ROTA, screening the suspected organs, assessing the risk and protecting the related population will be effective way to prevent and control further occurrence of ROTA.

Fresh osteochondral allografts-procurement and tissue donation in Europe

Fresh osteochondral allografts are a well-established treatment for large, full-thickness cartilage defects. The clinical outcome for carefully selected patients is very favorable, especially for the young and active and graft survival up to 25 years has been described in the literature. Furthermore, a high patient satisfaction rate has been reported, but the biggest obstacle to overcome is the availability of tissue for transplantation. Large fresh bone allografts for cartilage damage repair only can be harvested from organ donors following organ removal or cadaveric donors, preferably in the setting of an operation room to minimize possible contamination of the tissue. Apart from the logistic challenges this entails, an experienced recovery team is needed. Furthermore, the public as well as medical staff is much less aware of the possibility and requirements of tissue donation than organ donation and families of deceased are rarely approached for bone and cartilage donation. This review aims to highlight the current situation of organ and tissue donation in Europe with special focus on the processing of bones and possible safety and quality concerns. We analyze what may prevent consent and what might be done to improve the situation of tissue donation.

The Interaction of Osteoblasts With Bone-Implant Materials: 1. The Effect of Physicochemical Surface Properties of Implant Materials

This comparative study of various surface treatments of commercially available implant materials is intended as guidance for orientation among particular surface treatment methods in term of the cell reaction of normal human osteoblasts and blood coagulation. The influence of physicochemical surface parameters such as roughness, surface free energy and wettability on the response of human osteoblasts in the immediate vicinity of implants and on the blood coagulation was studied. The osteoblast proliferation was monitored and the expression of tissue mediators (TNF-α, IL-8, MMP-1, bone alkaline phosphatase, VCAM-1, TGF-β) was evaluated after the cell cultivation onto a wide range of commercially available materials (titanium and Ti6Al4V alloy with various surface treatments, CrCoMo alloy, zirconium oxide ceramics, polyethylene and carbon/carbon composite). The formation of a blood clot was investigated on the samples immersed in a freshly drawn whole rabbit blood using scanning electron microscope. The surfaces with an increased osteoblast proliferation exhibited particularly higher surface roughness (here Ra > 3.5 µm) followed by a high polar part of the surface free energy whereas the effect of wettability played a minor role. The surface roughness was also the main factor regulating the blood coagulation. The blood clot formation analysis showed a rapid coagulum formation on the rough titanium-based surfaces. The titanium with an etching treatment was considered as the most suitable candidate for healing into the bone tissue due to high osteoblast proliferation, the highest production of osteogenesis markers and low production of inflammatory cytokines and due to the most intensive blood clot formation.

Subsidence of the stem after impaction bone grafting for revision hip replacement using irradiated bone

Loss of bone stock is a major problem in revision surgery of the hip. Impaction bone grafting of the femur is frequently used when dealing with deficient bone stock. In this retrospective study a consecutive series of 68 patients (69 hips) who had revision of a hip replacement with femoral impaction grafting were reviewed. Irradiated bone allograft was used in all hips. Radiological measurement of subsidence of the stem, incorporation of the graft and remodelling was carried out and showed incorporation of the graft in 26 of 69 hips (38%). However, there was no evidence of trabecular remodelling. Moderate subsidence of 5 mm to 10 mm occurred in ten hips (14.5%), and massive subsidence of > 10 mm in five (7.2%). The results of this study are less favourable than those of others describing studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling noted in other series raises the question as to whether irradiated bone graft may be a significant factor influencing the post-operative outcome.

BMP-7 and CBFA1 in allograft bone in vivo bone formation and the influence of gamma-irradiation

An initial study showed that morselized human bone grafts were osteoconductive and osteoinductive when implanted in nude rat tibial window defects, and 25 kGy of gamma-irradiation significantly reduced those properties. The mechanism of the osteoinductivity and the influence of gamma-irradiation required further investigation. In this study we assessed the paraffin sections of seven morselized human bone grafts implanted into rat tibial defects for 3 weeks after being treated with 0, 15, or 25 kGy gamma-radiation respectively. Osteoclast-like cell counting and protein expressions of bone morphogenetic protein-7 (BMP-7), core binding factor alpha1 (CBFA1), and proliferating cell nuclear antigen (PCNA) were investigated and the positive signals were quantitatively analyzed. More new bone formation was observed in the 0 and 15 kGy groups compared with 25 kGy groups. The newly formed bones were found mainly from the intact cortex into the defects bridged by the implanted grafts. A dense staining of BMP-7 and CBFA1 was noted in the osteoblast-like cells in those areas. The BMP-7 and CBFA1 staining was also seen in the cells surrounding the implanted grafts in the centre areas of the defects in distance from the intact cortex. Quantitative analysis of immunohistochemical staining of the centre areas of the defects showed that gamma-irradiation (15 and 25 kGy) significantly reduced the expression of CBFA1 and BMP-7. In conclusion, morselized human bone grafts may contain some factors, which induced osteoblast lineage differentiation and bone formation and gamma-irradiation damages those bone inducing factors.

Serological Viral Testing of Cadaveric Cornea Donors

BACKGROUND

Cornea graft recipients are exposed to viral transmission from the donor. Cadaveric donor serum is often of poor quality and frequently yields falsely positive results in serological assays that may result in the graft being needlessly discarded.

OBJECTIVE

We examined the influence of the time of blood collection after death, and the macroscopic aspect of serum, on serological test results in cadaveric cornea donors.

METHODS

Five hundred sixty-five consecutive cadaveric cornea donors were systematically tested for serological markers of human immunodeficiency virus type 1 and 2, human T-cell leukemia virus type 1, hepatitis B and hepatitis C viruses (HCV). We studied the influence of the macroscopic aspect of the donor's serum and the time of blood collection after death on the results of serological testing and on the subsequent decision to use or discard the graft.

RESULTS

Twenty-one and a half percent of corneas were rejected on the basis of virological test results. We found significant relationships between the macroscopic aspect of serum at the time of testing and: (i) a positive, equivocal or discrepant result of immunoassays, for all markers except anti-HCV antibodies, (ii) non acceptance of cornea grafts, and (iii) the time of blood sampling after death.

CONCLUSIONS

The macroscopic aspect of postmortem blood samples is the best predictor of the specificity of serological testing in cornea donors. Serological results should be interpreted with care when serum is macroscopically abnormal, and cadaveric donors should not be sampled more than 12 hr after death.

When do tissues and cells become products? – Regulatory oversight of emerging biological therapies

Although therapeutics derived from biological sources have been subjected to regulatory oversight for some time, the products used in transplantation procedures have historically been exempt from this oversight. These products have been viewed as being part of medical practice rather than as the result of mainstream pharmaceutical manufacture. Furthermore, their unique source makes them difficult to assess in traditional regulatory systems based on the tenets of pharmaceutical quality control. With the increasing use of transplantation therapies to both replace dysfunctional organs and to influence genetic and metabolic processes, public health concerns on these therapies have increased. In addition, it is recognized that therapeutic claims for some of these interventions need to be properly assessed. These considerations have led the established regulatory agencies of the developed world to develop new regulatory paradigms for the products of transplantation practice. While a number of concerns have driven these developments, the minimization of infectious disease risk remains the paramount driver for introducing these regulatory systems. More than the regulation of medicines and medical devices manufactured in traditional pharmaceutical modes, the regulation of cell and tissue products is intimately linked to areas of public health policy and funding. This places regulators in a challenging position as they attempt to reconcile their roles as independent assessors with the needs of the overall public health framework. This is particularly difficult when considering measures which may affect access to life saving therapies. Regulators have recognized the need to assess these therapies through systems which incorporate consideration of risk-benefit ratios and include mechanisms for transparent and accountable release of products when full compliance to traditional concepts of manufacturing practice is not possible.

Trypanosoma cruzi: experimental parasitism of bone and cartilage

Trypanosoma cruzi causes Chagas' disease, a systemic infection that affects cells of meso-, endo-, and ectodermic origin. However, as far as we know, the presence of T. cruzi stages in bone has not been reported previously, and it has scarcely been investigated in cartilage. We inoculated 7- and 20-day-old (8 and 15 g) NMRI albino mice i.p. with metacyclic trypomastigotes from Rhodnius prolixus used for xenodiagnosis of mice previously infected with mammalian, human, and triatomines isolates, characterized by randomly amplified polymorphic DNA as zymodeme 1 (equivalent to T. cruzi I). Tissular parasitism (quantified according to the number of pseudocysts/50 fields 400x) showed amastigotes, intermediate forms, or trypomastigotes in sternum chondroblasts, osteoblasts, macrophages, and fibroblasts; chondrocyte and osteocyte invasion was rare. All isolates parasitized bone marrow macrophages, with few amastigotes. We observed marked associated myotropism, with or without inflammatory infiltration; there were small numbers of intensely parasitized mononuclear cells in perichondrium and periosteum. We discuss the results in relation to the marked differences of the T. cruzi tropism toward the different types of sternum cells, and, additionally, we outline the possibility of transmitting parasitized bone marrow through transplants. The fact of finding parasite stages in sternum bone and cartilage may be considered important due to the studies on Chagas' disease paleoparasitology that are based on histological and molecular analysis.

Preventing disease transmission by deceased tissue donors by testing blood for viral nucleic acid

Nucleic acid testing (NAT) has reduced the risk of transmitting infectious disease through blood transfusion. Currently NAT for HIV-1 and HCV are FDA licensed and performed by nearly all blood collection facilities, but HBV NAT is performed under an investigational study protocol. Residual risk estimates indicate that NAT could potentially reduce disease transmission through transplanted tissue. However, tissue donor samples obtained post-mortem have the potential to produce an invalid NAT result due to inhibition of amplification reactions by hemolysis and other factors. The studies reported here summarize the development of protocols to allow NAT of deceased donor samples with reduced rates of invalid results. Using these protocols, inventories from two tissue centers were tested with greater than 99% of samples producing a valid test result.

Clinical effectiveness of processed and unprocessed bone

Bone allografts have been used clinically for a number of years. Understanding the biology of bone healing and the impact that bone banking has on this helps to improve the methodologies used in increasing the quality and safety of banked bone. Banked bone in its various forms has been used in a variety of surgical procedures, and although there is no doubt that it is clinically effective, most of the studies have been retrospective and non-randomized. The review attempts to summarize some of the data in this area and highlights some of the difficulties encountered in such work. Although there is no doubt that bone banking is nowadays better controlled, there are ever-increasing pressures to produce bone that is as safe as possible with the least impact on its effectiveness. This can only be achieved if the requirements of the providers and users of bone are better understood.

Challenges in the Testing of Non-Heart-Beating Cadavers for Viral Markers: Implications for the Safety of Tissue Donors

Natural changes that occur in blood and tissue after death may result in false positive results in antigen and antibody detection tests performed to identify markers of viral infection in potential tissue donors. Such tissue, which might otherwise be acceptable for therapeutic purposes, would not meet current standards for safe tissue banking. This is especially important in the context of insufficiency in the tissue supply. In this study, a series of blood samples collected during routine post-mortem examination was assayed using a range of commercially available kits for the detection of HBsAg, anti-HCV and anti-HIV 1 + 2 antibody/antigen. Results of tests on 104 samples collected from 97 individuals indicate that some kits result in a higher number of initial reactive samples than others. Approximately 40% of samples were reactive in one or more HBsAg assay, less than 10% in at least one anti-HIV kit and only 1 sample at low level on an anti-HCV kit. Liver or lymph node samples from individuals whose serum sample gave reactive results in antigen/antibody assays were tested for viral nucleic acid in the corresponding nucleic acid amplification test. Only one individual's sample was confirmed to test positive for HBsAg in a confirmatory neutralisation test and by nucleic acid amplification technology, and a second individual whose serum was scored reactive for anti-HCV, but negative for HBsAg, had a liver sample which was HBV DNA positive and HCV RNA negative. The results of the study indicate that antibody/antigen assays are not as specific as NAT using state of the art DNA extraction techniques. Both types of assay complement each other and used together will help assure the safety of tissues for transplantation.

Bacterial Contamination of Tissue Allografts – Experiences of the Donor Tissue Bank of Victoria

The aim of this study is to report the experience of the Donor Tissue Bank of Victoria with bacteria isolated from musculoskeletal, skin and cardiac allografts retrieved from cadaveric donors. The results of all quality control samples for bacterial culture, taken during retrieval and processing of allografts at the DTBV for a 12 month period, were extracted and analysed. It was found that 15.7% of skin, 15.1% of heart valves and 5.8% of musculoskeletal samples had positive culture results. The number and types of organisms isolated varied with tissue type. The most commonly isolated organisms were Staphylococcus species (including S. aureus). The identity of the isolate and the number of positive specimens from the same donor were considerations in the decision concerning the suitability of tissue for subsequent implantation.

Infection in massive bone allografts

We studied a series of 945 patients who received cadaveric allografts implanted for nonpelvic bone or soft tissue tumor lesions since 1971. We specifically were interested in the role of infection in the graft process, and, more specifically its history, frequency, and affect on outcome. Primary infections (not related to reoperations for nonunions or fractures of the graft) occurred in 75 patients (7.9%), and an additional 46 patients had infections related to reoperations, increasing the total number of patients with infections to 121 (12.8%). The highest frequency of infection occurred in patients with soft tissue tumors, radiated sites, Musculoskeletal Tumor Society Stage IIB tumors, or surgeries consisting of an allograft arthrodesis. Most of the infected grafts failed; however, none of the patients died. One patient had hepatitis C develop, and one patient became HIV positive after receiving the virus from a blood transfusion. A comparison with other series of surgically treated patients, including those receiving metallic devices, suggests that the infection rate may be related to the surgery or the graft's immunologic resistance, rather than the graft. The problem of infection is a major issue for tumor surgeons. Suggestions regarding how to decrease the frequency of this complication are presented.

Biological properties of the intervertebral cages made of titanium containing a carbon-carbon composite covered with different polymers

Intervertebral cages are used in orthopaedics for stabilization of injured lumbar parts of vertebral columns. Our study provides preliminary results of tests of the biological properties of titanium cages with a variously modified carbon/carbon composite (C/C) core. This core was produced from a C/C composite modified by hydrogel materials based on poly(2-hydroxyethyl methacrylate) (HEMA) enriched with 1% collagen or 35% methylmethacrylate or 30% terc-butylmethacrylamide. We evaluated the adhesion of the cells to the tested material coating using an in vitro study of the metabolic activity and cytokine production of the cells (TNF-alpha, IL-8). We studied the biocompatibility of intervertebral cages coated with different copolymers under in vivo condition and in an implantation experiment in the porcine femurs. Both in vitro and in vivo results revealed favourable biotolerance of the use system. Modification of the composite HEMA with the use of collagen seems to have a more positive effect on the new bone tissue formed around the implanted devices than HEMA copolymerized with methylmethacrylate or terc-butylmethacrylamide.

Elimination of false-negative hepatitis C virus RNA results by removal of inhibitors in cadaver-organ donor blood specimens

Detection of viral nucleic acids in blood samples from cadavers is often difficult because of inhibition of the reverse transcriptase (RT) or polymerase chain reaction (PCR) steps by substances present in the samples. A robust method for the extraction and detection of hepatitis C virus (HCV) RNA from cadaver blood samples by polymerase chain reaction RT-PCR has been developed on the basis of the Qiagen QIAamp DNA mini kit extraction system (Basel, Switzerland). Twenty of 36 samples tested were positive for HCV RNA. Six of the 16 HCV-antibody- and RNA-negative samples contained inhibitors that were successfully removed by pretreatment of samples with the Qiagen AX matrix before extraction.

Osteogenic stem cells and orthopedic engineering: summary and update

The use of osteogenic stem cells or osteoprogenitors to reconstruct skeletal tissues is a popular area of research investigation with high potential for successful use of tissue-engineering principles in orthopedics. Recent studies demonstrate the migration of marrow-derived stem cells to skeletal sites and the proliferation and differentiation at local tissue sites and support possibilities for assessing the successful uses of human osteoprogenitors in the treatment of bone deficiency diseases. In addition, the development of gene therapy procedures in these and other conditions is now considered an achievable goal with the use of these primitive marrow cells.

Viruses in the mammalian male genital tract and their effects on the reproductive system

This review describes the various viruses identified in the semen and reproductive tracts of mammals (including humans), their distribution in tissues and fluids, their possible cell targets, and the functional consequences of their infectivity on the reproductive and endocrine systems. The consequences of these viral infections on the reproductive tract and semen can be extremely serious in terms of organ integrity, development of pathological and cancerous processes, and transmission of diseases. Furthermore, of essential importance is the fact that viral infection of the testicular cells may result not only in changes in testicular function, a serious risk for the fertility and general health of the individual (such as a fall in testosteronemia leading to cachexia), but also in the possible transmission of virus-induced mutations to subsequent generations. In addition to providing an exhaustive account of the data available in these domains, this review focuses attention on the fact that the interface between endocrinology and virology has so far been poorly explored, particularly when major health, social and economical problems are posed. Our conclusions highlight the research strategies that need to be developed. Progress in all these domains is essential for the development of new treatment strategies to eradicate viruses and to correct the virus-induced dysfunction of the endocrine system.

Infectious disease issues in xenotransplantation

Xenotransplantation, the transplantation of living organs, tissues, or cells from one species to another, is viewed as a potential solution to the existing shortage of human organs for transplantation. While whole-organ xenotransplantation is still in the preclinical stage, cellular xenotransplantation and extracorporeal perfusion applications are showing promise in early clinical trials. Advances in immunosuppressive therapy, gene engineering, and cloning of animals bring a broader array of xenotransplantation protocols closer to clinical trials. Despite several potential advantages over allotransplantation, xenotransplantation encompasses a number of problems. Immunologic rejection remains the primary hindrance. The potential to introduce infections across species barriers, another major concern, is the main focus of this review. Nonhuman primates are unlikely to be a main source for xenotransplantation products despite their phylogenetic proximity to humans. Genetically engineered pigs, bred under special conditions, are currently envisaged as the major source. Thus far, there has been no evidence for human infections caused by pig xenotransplantation products. However, the existence of xenotropic endogenous retroviruses and the clinical evidence of long-lasting porcine cell microchimerism indicate the potential for xenogeneic infections. Thus, further trials should continue under regulatory oversight, with close clinical and laboratory monitoring for potential xenogeneic infections.

The effects of processing and low dose irradiation on cortical bone grafts

The authors studied the effects of standard processing and preprocessing low dose gamma irradiation (1.5 Mrad) on the strength and incorporation of syngeneic and allogeneic cortical bone grafts. Bilateral femoral middiaphyseal 8-mm segmental defects in 120 male Fisher rats were stabilized with internal fixation. Each defect received one of six types of grafts: fresh syngeneic, processed syngeneic, irradiated processed syngeneic, fresh allogeneic, processed allogeneic, and irradiated processed allogeneic grafts. Graft processing included soaking in 70% ethanol and deep freezing for preservation. Irradiation was performed by 60Co source immediately before processing. Grafts were evaluated by histologic analysis, histomorphometric analysis, and biomechanical testing at 4 and 6 months after surgery. Graft treatment, either processing or irradiation processing, did not affect consistently or significantly the incorporation of syngeneic or allogeneic grafts. Graft allogenicity was the major determinant of the revascularization and the histologic pattern of graft incorporation. Processed and irradiated processed allogeneic grafts gained compressive strength with time and were as strong as syngeneic grafts at 6 months. Biomechanical and histologic data from this study suggest that standard processing and preprocessing low dose irradiation do not compromise the natural course of allogeneic cortical bone graft incorporation.

Efficacy and kinetics of glycerol inactivation of HIV-1 in split skin grafts

Allogeneic split skin grafts are used widely in the treatment of burns. The relative simplicity of glycerol preservation of skin suggests it will be used increasingly in areas of high HIV-1 seroprevalence. The ability of glycerol preservation to inactivate HIV-1 present in skin graft infected in vitro was determined using a macrophage tropic strain HIV-1 as a cell-free virus suspension, within infected PBMCs, or within in vitro HIV-1 infected fresh cadaveric split skin. Different temperatures and concentrations of glycerol were used and infectivity determined by coculture with mitogen activated peripheral blood mononuclear cells (PBMCs) and measurement of reverse transcriptase activity after 7-10 days. Cell-free HIV-1 was inactivated within 30 min at 4 degrees C in glycerol concentrations of 70% or higher. During similar exposure cell- or skin-associated HIV-1 titer was reduced but not eliminated with 70% and 85% glycerol at 4 degrees C. HIV-1 was recovered consistently from skin stored in 85% glycerol at 4 degrees C for up to 72 hr but virus isolation was infrequent after storage for more than 5 days. At 20 degrees C or 37 degrees C, 70% or 85% glycerol could inactivate cell- or skin-associated HIV-1 within 8 hr. The initial glycerolization procedures and the storage at 4 degrees C eliminated effectively HIV-1 from skin.

Evaluation of serological screening of cadaveric sera for donor selection for cornea transplantation

Human corneas are explanted for grafting as late as 72 h after death, for example, from medical examiner cases. Currently, infection of the donor with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) is excluded in most cornea banks by serological testing of the cadaveric serum only. The reliability of this strategy was investigated by testing paired cadaveric and premortem sera of 33 potential donors. Results were discordant in 17 of 33 donors by at least one assay. Most frequently, HBsAg enzyme-linked immunosorbent assay (ELISA) yielded false-positive results with the cadaveric serum (16 of 33 serum pairs). Virus safety of the graft was affected in a single case, which was HCV antibody negative in the cadaveric serum, but positive in the premortem serum (confirmed by HCV-RIBA strip immunoassay). Forensic DNA profiling by polymerase chain reaction (PCR) of both serum samples confirmed that these were derived from the same individual. In conclusion, the results indicate that serological testing of cadaveric sera is not a reliable method for screening of potential cornea donors, and may not be sufficient for the virus safety of cornea grafts. Therefore, other screening strategies such as detection of viral nucleic acids by PCR should be evaluated.

Use of frozen cranial vault bone allografts in the repair of extensive cranial bone defects

In cranioplasty complexity is proportional to the size of the detect, particularly if greater than 50 cm2. If the patient's own bone flap is not available, allogenic frozen bone graft can be used instead. Between June 1990 and June 1995 twenty cranioplasties with allogenic frozen bone grafts were performed. Age of patients ranged between 23 and 63 years (average 38.4 years). Male/female ratio was 2:1.7. Size of craniectomy ranged between 65 and 150 cm2 (average 83.3 cm2). Follow-up ranged between 10 and 58 months (average 41 months). Donors were tested to rule out transmissible diseases, infections, sepsis and/or cancer. Bone grafts were removed under aseptic conditions, microbiological cultures were taken, wrapped in a gauze soaked with Gentamicin sulphate and Bacitracin, sealed in three sterilised vinyl plastic bags, and stored in a deep freezer for a minimum of 30 days (range 36-93 days, average 67 days), at a temperature of -80 degrees C. Grafts were placed in the defect after a step was carved on its borders to facilitate the contact between host and graft. Vancomycin 1 g. IV/12 hours and Ceftriaxone 1 g. IV/12 hours were administered for five days. Grafts were covered by means of scalp flaps. Only one required a musculocutaneous free flap. None was exposed, extruded or had to be removed. Plain skull X-ray studies showed progressive remodelling of the grafts. Partial resorption was observed in two (2/20, 10%) and loss of thickness in another 3/20 (15%), but with no changes in the contour. Biopsies were taken in 3/20 (15%) cases at a second surgical procedure. Areas of osteoclastic resorptive activity mixed with others of osteoblastic bone apposition, showed replacement with new bone. We conclude that cranial vault frozen allografts are a good alternative to autologous bone when the latter is absent or not present in sufficient amount.