Banking of cryopreserved iliac artery and vein homografts: clinical uses in transplantation.

Iliac artery and vein homografts are critical for revascularization in living-donor liver transplantation. Since 2010, National Cardiovascular Homograft Bank and National University Hospital have collaborated in the pioneer endeavor of banking iliac vessel homografts for such surgeries in Singapore. This article aims to demonstrate that the processing, decontamination and cryopreservation techniques that our bank follow, help preserve iliac vessel homografts for a longer duration as compared to homografts preserved using short-term preservation techniques. This paper reports the first 4 years of post-operative outcome for recipients as a preliminary report for a longer-term outcome study. Criteria for donor assessment, techniques of iliac vessel homograft recovery, processing, decontamination, cryopreservation and storage according to the American Association of Tissue Banks standards are also described. From 2010 until 2013, we discovered of the iliac vessel homografts processed, 17 (94.4 %) were suitable for clinical use. Nine iliac artery grafts (64 %) and one iliac vein graft (14 %) were implanted. Irrespective of vessel type, homografts <90 mm in length were of little use. Of the nine current iliac vessel homograft recipients, eight patients (89 %) had living-donor liver transplantation and one patient (11 %) had reconstruction of the right internal carotid artery after resection of an aneurysm. Our preliminary results supports existing literatures that suggest cryopreserved iliac vessel homografts can be successfully used for revascularization in liver transplantation and reconstruction of carotid artery. Encouraging short-term post-operative patient outcomes have been achieved, with no report of adverse event attributed to implanted homografts. We believe that our processing, decontamination and cryopreservation techniques have helped preserve the homografts for longer duration as compared to homografts preserved using short-term preservation techniques.

Homograft banking in Singapore: two years of cardiovascular tissue banking in Southeast Asia.

Established in 2008, the National Cardiovascular Homograft Bank (NCHB) has been instrumental in creating an available supply of cardiovascular tissues for implantation in Singapore. This article introduces its collaboration with Singapore General Hospital Skin Bank Unit. The procedure of homograft recovery, processing, cryopreservation and quality assurance are presented. Since its establishment, the NCHB has followed the guidelines set by the Ministry of Health Singapore and the American Association of Tissue Banks. A total of 57 homografts had been recovered and 40 homografts were determined to be suitable for clinical use. The most significant reasons for non-clinical use are positive microbiological culture or unsuitable graft condition. Crucial findings prompted reviews and implementation of new procedures to improve the safety of homograft recipients. These include (1) a change in antibiotic decontamination regime from penicillin and streptomycin to amikacin and vancomycin after a review and (2) mandating histopathogical examination since the discovery of cardiac sarcoidosis in a previously undiagnosed donor. Further, the NCHB also routinely performs dengue virus screening, for donors suspected of dengue infection. Cultural factors which affect the donation rate are also briefly explored. By 2010, 31 homografts had been implanted into recipients with congenital or acquired heart valve conditions. More than half of these recipients were children. Post-operative outcomes had been encouraging, with no report of adverse events attributed to implanted homografts.

A Review of Skin Banking Guidelines and Standards Worldwide: Towards the Harmonization of Guidelines for Skin Banking in Therapeutic Applications for the Regions under the Asia Pacific Burn Association (APBA).

Currently, there are no harmonized guidelines which govern skin banking in the Asia Pacific region. Therefore, skin banks are either unregulated or rely on their nation's legislation or international accreditation to uphold their quality standards. A new set of skin banking guidelines was developed through a comprehensive review and collation of best international practices for the Asia Pacific Burn Association (APBA) members, from donor screening and testing, to skin recovery, processing, storage and distribution, and quality assurance. National regulatory requirements reviewed include the European directives, Australia's Therapeutic Goods Administration and Singapore's tissue banking standards. Further technical and quality management recommendations are referenced from the American Association of Tissue Banks (AATB), the United States Food and Drug Administration standards and guidance documents, various relevant European guides, Japanese Society of Tissue Transplantation guidelines and the Asia Pacific Association of Surgical Tissue Banking. Adapted mainly from the AATB standards, the new Asia Pacific Burn Association Guidelines for Skin Banking in Therapeutic Applications offer a comprehensive manual, addressing: governance and contracts; staff responsibilities; quality management; facilities, equipment and supplies management; donor consent and testing; and recommendations of good practices pertaining to skin recovery, processing, storage and distribution. Besides complementing current generic regulations, they provide technical specifications of major aspects unaddressed in most legislations. This inaugural set of new regional skin banking guidelines would be a start for regional members of the APBA to adopt, and will hopefully culminate in a set of standards so that, in the long run, skin allografts from this region can be of similar quality, which can simplify import process and facilitate the exchange of allografts between members.

Validation of microbiological testing in cardiovascular tissue banks: results of a quality round trial.

OBJECTIVES: Surgeons needing human cardiovascular tissue for implantation in their patients are confronted with cardiovascular tissue banks that use different methods to identify and decontaminate micro-organisms. To elucidate these differences, we compared the quality of processing methods in 20 tissue banks and 1 reference laboratory. We did this to validate the results for accepting or rejecting tissue. We included the decontamination methods used and the influence of antibiotic cocktails and residues with results and controls. The minor details of the processes were not included. METHODS: To compare the outcomes of microbiological testing and decontamination methods of heart valve allografts in cardiovascular tissue banks, an international quality round was organized. Twenty cardiovascular tissue banks participated in this quality round. The quality round method was validated first and consisted of sending purposely contaminated human heart valve tissue samples with known micro-organisms to the participants. The participants identified the micro-organisms using their local decontamination methods. RESULTS: Seventeen of the 20 participants correctly identified the micro-organisms; if these samples were heart valves to be released for implantation, 3 of the 20 participants would have decided to accept their result for release. Decontamination was shown not to be effective in 13 tissue banks because of growth of the organisms after decontamination. Articles in the literature revealed that antibiotics are effective at 36°C and not, or less so, at 2-8°C. The decontamination procedure, if it is validated, will ensure that the tissue contains no known micro-organisms. CONCLUSIONS: This study demonstrates that the quality round method of sending contaminated tissues and assessing the results of the microbiological cultures is an effective way of validating the processes of tissue banks. Only when harmonization, based on validated methods, has been achieved, will surgeons be able to fully rely on the methods used and have confidence in the consistent sterility of the tissue grafts. Tissue banks should validate their methods so that all stakeholders can trust the outcomes.

Psychosocial Factors, Knowledge and Attitudes Influencing Skin and Heart Valve Donation among Healthcare Professionals in Singapore.

INTRODUCTION: In Singapore, tissue donation is covered under the Medical (Therapy, Education and Research) Act. The objective of this study is to review the demographic and psychosocial factors, which may cause hesitation/unwillingness amongst healthcare professionals towards tissue donation. MATERIALS AND METHODS: A survey comprising 18-items was conducted at the Singapore General Hospital and National Heart Centre Singapore. A total of 521 individuals participated in the survey. Descriptive statistics were performed for the demographic profiles of participants, the factors leading to the support of tissue donation, reasons for hesitation/reluctance to donate tissue and motivating factors to discuss tissue donation with next-of-kin. Pearson's chi-square and Fisher's exact tests were employed to assess possible association between various factors and support towards tissue donation. Analyses were performed using Statistical Package for Social Sciences V.21.0 software. RESULTS: A total of 64.9% of participants had heard about skin donation; 48.9% had heard about heart valve donation; 4.5% were tissue pledgers. The primary reason for pro-donation was the altruism of "improving someone's quality of life". However, a majority stated they "can decide this in the later part of life" as their main reason for hesitation; 82.3% were willing to discuss their tissue donation wish with next-of-kin, while 53.1% were likely to make the decision of donation on behalf of their deceased next-of-kin. CONCLUSION: RESULTS highlighted important psychosocial and professional factors that influence the hesitation/ reluctance towards donation. Hence, there is a need to re-strategise educational efforts in accordance with the target audiences and address specific misconceptions and concerns.

International heart valve bank survey: a review of processing practices and activity outcomes.

A survey of 24 international heart valve banks was conducted to acquire information on heart valve processing techniques used and outcomes achieved. The objective was to provide an overview of heart valve banking activities for tissue bankers, tissue banking associations, and regulatory bodies worldwide. Despite similarities found for basic manufacturing processes, distinct differences in procedural details were also identified. The similarities included (1) use of sterile culture media for procedures, (2) antibiotic decontamination, (3) use of dimethyl sulfoxide (DMSO) as a cryoprotectant, (4) controlled rate freezing for cryopreservation, and (5) storage at ultralow temperatures of below -135°C. Differences in procedures included (1) type of sterile media used, (2) antibiotics combination, (3) temperature and duration used for bioburden reduction, (4) concentration of DMSO used for cryopreservation, and (5) storage duration for released allografts. For most banks, the primary reasons why allografts failed to meet release criteria were positive microbiological culture and abnormal morphology. On average, 85% of allografts meeting release criteria were implanted, with valve size and type being the main reasons why released allografts were not used clinically. The wide variation in percentage of allografts meeting release requirements, despite undergoing validated manufacturing procedures, justifies the need for regular review of important outcomes as cited in this paper, in order to encourage comparison and improvements in the HVBs' processes.

From penicillin-streptomycin to amikacin-vancomycin: antibiotic decontamination of cardiovascular homografts in Singapore.

BACKGROUND: In February 2012, the National Cardiovascular Homograft Bank (NCHB) became the first tissue bank outside of North America to receive accreditation from the American Association of Tissue Banks. From 2008 to 2009, NCHB had been decontaminating its cardiovascular homografts with penicillin and streptomycin. The antibiotic decontamination protocol was changed in January 2010 as amikacin and vancomycin were recommended, in order to cover bacteria isolated from post-recovery and post- antibiotic incubation tissue cultures. AIM: The objective of this study is to determine the optimal incubation conditions for decontamination of homografts by evaluating the potencies of amikacin and vancomycin in different incubation conditions. Retrospective reviews of microbiological results were also performed for homografts recovered from 2008 to 2012, to compare the effectiveness of penicillin-streptomycin versus the amikacin-vancomycin regimens. METHODS: Based on microbiological assays stated in United States Pharmacopeia 31, potency of amikacin was evaluated by turbidimetric assay using Staphylococcus aureus, while vancomycin was by diffusion assay using Bacillus subtilis sporulate. Experiments were performed to investigate the potencies of individual antibiotic 6-hours post incubation at 4°C and 37°C and 4°C for 24 hours, after the results suggested that amikacin was more potent at lower temperature. FINDINGS: Tissue incubation at 4°C for 24 hours is optimal for both antibiotics, especially for amikacin, as its potency falls drastically at 37°C. CONCLUSION: The decontamination regimen of amikacin-vancomycin at 4°C for 24 hours is effective. Nevertheless, it is imperative to monitor microbiological trends closely and evaluate the efficacy of current antibiotics regimen against emerging strains of micro-organisms.