American Association Of Blood Banks Research Articles

Cryoprecipitate-removed plasma 'cryo-removed plasma' as a source of factor IX in the treatment of haemophilia B.

Fresh frozen plasma (FFP) is the main source of factor IX (FIX) in the treatment of bleeding episodes of haemophilia B in the Philippines. Cryoprecipitate-removed plasma otherwise known in the Philippines as cryosupernate, is a by-product of cryoprecipitate preparation. These blood products expire in storage or are just thrown- away because of less demand for clinical use. By theory, this product should have almost the same amount of FIX as in FFP, therefore can be used in the treatment of haemophilia B. There is no local data on the actual FIX content of the cryoprecipitate-removed plasma. Hence, the authors established these data to support the use of this product. Eighty-three bags of cryoprecipitate-removed plasma received from three different blood banks in Manila, Philippines were tested for FIX activity using an activated partial thromboplastin time (APTT)-based one-stage FIX assay. The FIX content in each bag of cryoprecipitate-removed plasma was calculated by multiplying its volume in mL with that of FIX activity per mL of plasma measured in vitro. The total mean FIX content per bag was 212.20 U (+/-88.98) exceeding the contents set by the American Association of Blood Banks (AABB, 70-90 U). The mean FIX activity per bag was 127.62% (+/-38.23) with the mean volume of 164.28 mL (+/-52.23). Statistically significant difference on volume (P = 0.000) was found across the three sources resulting to a significant variation of the actual FIX content (P = 0.000).

Impact of new AABB guidelines on hepatitis B and C testing among Saudi blood donors

This study aims to compare the advantages and disadvantages of implementing the new American Association of Blood Banks (AABB) guidelines for hepatitis B and C against its old criteria for screening blood donors. Between July 1995 and December 2002, 63,368 consecutive blood donors were screening for hepatitis B and C according to the new guidelines. Cost and prevalence were analysed and compared with those found using the old AABB guidelines prior to July 1995. The overall percentage rate of deferred donors showed a significantly decrease to 19.3% in 2002, compared to 58.4% before July 1995 (P < 0.001). The new prevalence of hepatitis B and C among Saudi blood donors was found to be 1.7% and 0.6%, respectively, compared to 4% and 1.4%, respectively, under the old AABB guidelines. This resulted in a significant increase in the number and yield of blood units, and a decrease in the prevalence of hepatitis B and C was observed among screened donors. Using the new AABB guidelines, the estimated direct cost of donor screening for hepatitis B and C decreased significantly from $42.8 per donor to $29.2 per donor (P<0.001).

Risk and prevention of transfusion-related sepsis.

Transfusion-related sepsis is both the oldest recognized and most common transfusion-associated infectious risk. Despite an increased awareness and recognition of this problem, particularly with room-temperature stored platelets, strategies to prevent or reduce the occurrence of this problem have proved daunting. With the recent FDA approval of culture methods for platelet bacterial testing and the promulgation of accreditation standards by the College of American Pathologists and American Association of Blood Banks to limit and detect platelet bacterial contamination, it is anticipated that the frequency of this problem will now begin to diminish. As methods to reduce and/or inactivate pathogens emerge, it is hoped that transfusion-related sepsis will essentially disappear.

American Association of Blood Banks 2002‐2003 Board of Directors

TransfusionVolume 43, Issue 9s p. ii-ii American Association of Blood Banks 2002-2003 Board of Directors First published: 27 August 2003 https://doi.org/10.1046/j.1537-2995.43.9s.4.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume43, Issue9sSeptember 2003Pages ii-ii RelatedInformation

Professor Walter Morgan

Professor Walter Morgan

Bacterial contamination of blood components: risks, strategies, and regulation: joint ASH and AABB educational session in transfusion medicine.

Bacterial contamination of transfusion products, especially platelets, is a longstanding problem that has been partially controlled through modern phlebotomy practices, refrigeration of red cells, freezing of plasma and improved materials for transfusion product collection and storage. Bacterial contamination of platelet products has been acknowledged as the most frequent infectious risk from transfusion occurring in approximately 1 of 2000-3000 whole-blood derived, random donor platelets, and apheresis-derived, single donor platelets. In the US, bacterial contamination is considered the second most common cause of death overall from transfusion (after clerical errors) with mortality rates ranging from 1:20000 to 1:85000 donor exposures. Estimates of severe morbidity and mortality range from 100 to 150 transfused individuals each year. Concern over the magnitude and clinical relevance of this issue culminated in an open letter calling for the "blood collection community to immediately initiate a program for detecting the presence of bacteria in units of platelets." Thereafter, the American Association of Blood Banks (AABB) proposed new standards to help mitigate transfusion of units that were contaminated with bacteria. Adopted with a final implementation date of March 1, 2004, the AABB Standard reads "The blood bank or transfusion service shall have methods to limit and detect bacterial contamination in all platelet components." This Joint ASH and AABB Educational Session reviews the risks, testing strategies, and regulatory approaches regarding bacterial contamination of blood components to aid in preparing practitioners of hematology and transfusion medicine in understanding the background and clinical relevance of this clinically important issue and in considering the approaches currently available for its mitigation, as well as their implementation. In this chapter, Drs. Hillyer and Josephson review the background and significance of bacterial contamination, as well as address the definitions, conceptions and limitations of the terms risk, safe and safety. They then describe current transfusion risks including non-infectious serious hazards of transfusion, and current and emerging viral risks. In the body of the text, Dr. Blajchman reviews the prevalence of bacterial contamination in cellular blood components in detail with current references to a variety of important studies. He then describes the signs and symptoms of transfusion-associated sepsis and the sources of the bacterial contamination for cellular blood products including donor bacteremia, and contamination during whole blood collection and of the collection pack. This is followed by strategies to decrease the transfusion-associated morbidity/mortality risk of contaminated cellular blood products including improving donor skin disinfection, removal of first aliquot of donor blood, pre-transfusion detection of bacteria, reducing recipient exposure, and pathogen reduction/inactivation. In the final sections, Drs. Vostal, Epstein and Goodman describe the regulations and regulatory approaches critical to the appropriate implementation of a bacterial contamination screening and limitation program including their and/or the FDA's input on prevention of bacterial contamination, bacterial proliferation, and detection of bacteria in transfusion products. This is followed by a discussion of sampling strategy for detection of bacteria in a transfusion product, as well as the current approval process for bacterial detection devices, trials recommended under "actual clinical use" conditions, pathogen reduction technologies, and bacterial detection and the extension of platelet storage.

Grading of qualitative and quantitative responses in the PI proficiency survey of the College of American Pathologists for mailings in 1997–2000

The PI Survey offered jointly by the American Association of Blood Banks (AABB) and the College of American Pathologists (CAP) provides biological samples for proficiency testing that mirror paternity casework samples. A grading scheme providing for three levels of performance (good, acceptable, and unacceptable) has been developed for responses provided by subscribers. Reported here is a review of the performance of participants using RFLP and PCR/STR methods for the 1997–2000 period. In general, laboratories reporting phenotypes and paternity index values using RFLP methods exhibited a fairly constant rate of unacceptable responses over the 4-year period. In contrast, laboratories using PCR/STR systems improved dramatically in the frequency of unacceptable responses (an average of 3.5% for mailings in 1997 vs. 0.7% for mailings in 2000). A comparison of unacceptable responses for RFLP and PCR/STR methods over the 4-year period shows that whereas phenotype designations for PCR/STR systems is better than for RFLP systems, the opposite is true for reported paternity index values.

Bacterial contamination of blood components.

1. Linda A Smith, PhD CLS(NCA)[⇑][1] 1. is Professor and Graduate Program Director at the University of Texas Health Science Center, San Antonio TX 2. Michelle S Wright-Kanuth, PhD CLS(NCA) 1. is Associate Professor, Department of Clinical Laboratory Sciences, University of Texas Medical Branch, Galveston TX 1. Address for correspondence: Linda A Smith PhD CLS(NCA), Professor and Graduate Program Director, Department of Clinical Laboratory Sciences, University of Texas Health Science Center, 7703 Floyd Curl Dr, San Antonio TX 78229-3900. (210) 567-6689, (210) 567-8875 (fax). smithla{at}uthscsa.edu As discussed in one of the companion articles, significant progress has been made in reducing the transfusion transmission of viral infections such as hepatitis B, hepatitis C, and HIV. Serologic testing of donors has decreased the risk for acquiring some viral diseases to less than one in a million. Now however, bacterial contamination of blood products has assumed a major role as a cause of morbidity and mortality in recipients of blood products.1,2 Although overall risk for acquiring a transfusion-transmitted bacterial infection is still relatively low, methods to detect infected donors are not available as they are for detection of virally-infected donors. Therefore, detection of bacterial contamination is more problematic and is usually recognized only when the recipient has a severe reaction following administration of the blood component. In fact, after acute hemolytic transfusion reactions, bacterial sepsis is the next most frequent causes of transfusion related fatalities.3,4 In this article we will discuss the major organisms associated with bacterial contamination of blood components, studies of prevalence of bacterial contamination and transfusion associated sepsis, and the methods developed or in development to detect and/or prevent contamination. BACTERIAL CONTAMINATION Bacterial contamination of blood units occurs at any one of the following points: collection, processing, pooling of components, or transfusion. Infrequently, it may be due to transient bacteremia in the donor.5-7 High bacterial concentrations are often responsible for a serious septic or fatal reaction in the recipient with most of these reactions occurring in the elderly, neonates, or patients immunocompromised by illness or… ABBREVIATIONS: AABB = American Association of Blood Banks; BaCon = bacterial contamination associated with transfusion reactions); CFU = colony forming units; RBC = red blood cell; SHOT = serious hazards of transfusion; UVA = ultraviolet A light. [1]: #corresp-1

A support group for patients who have recovered from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS): The six-year experience of the Oklahoma TTP-HUS Study Group.

A support group for patients who have recovered from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS), named The Oklahoma TTP-HUS Study Group, has been a successful program for 6 years. This group has met 3 times each year with an average attendance of 16 former patients; in addition, an average of 14 family members and friends have attended each meeting. Eighty-four percent of patients who attended a meeting were women as compared to 68% women among those who did not attend (P = 0.016). Twenty-three percent of patients who attended a meeting have relapsed as compared to 8% among those who did not attend (P = 0.006). There was also a difference in the rates of attendance among the different clinical categories of patients (P < 0.001). A survey of former patients, as well as their families and friends, documented that interest in learning more about TTP-HUS and talking with other people who have had TTP-HUS were principal motivations for attending the meetings. The meetings of The Oklahoma TTP-HUS Study Group have been successful not only for support of former patients but also for research. Long-term patient follow-up has been facilitated and the group discussions have revealed previously unreported persistent problems with cognitive ability and endurance. A survey of member centers of the American Association of Blood Banks and America's Blood Centers revealed no similar programs for patients who have recovered from TTP-HUS. The absence of a support group for TTP-HUS in the national survey contrasts to the 274 patient support groups and related wellness/education classes, including some for rare disorders, currently active in the Oklahoma City metropolitan area. The experience of The Oklahoma TTP-HUS Study Group suggests that it serves a previously unmet need.

Practical issues in therapeutic apheresis.

Although therapeutic plasma exchange is known to be the most effective and efficient therapeutic modality for some disorders such as thrombotic thrombocytopenic purpura and hyperviscosity syndrome, no standard protocol of plasma exchange has been developed. A protocol based on evidence needs to be established for standard of care. It should include exchange volume, replacement fluid, frequency, and end point. Indication of plasma exchange is not always clear because prospective randomized clinical trials, especially blinded trials, are difficult to perform. The standard guideline is now available from Category 1 to Category 4 and is published by the American Association of Blood Banks and the American Society for Apheresis. Each institution should establish its own pheresis guideline and protocol for each disorder.

Choice of human plasma preparations for transfusion.

HE RECENT licensure of pooled plasma, solvent/detergent treated (PLAS + SD| V.I. Technologies, Melville, NY) by the US Food and Drug Administration (FDA) brings to three the number of plasma preparations available for transfusion in the United States. The other two preparations are fresh frozen plasma, donor-retested (FFPDR), and the traditional fresh frozen plasma (FFP) product. The newer products have been developed to address concerns about infectious disease transmission by transfusion. Although the therapeutic indications of these three plasma products are fundamentally the same, they differ in their potential to transmit infectious agents, in cost, and in availability. An ad hoc Committee of the American Association of Blood Banks summarized the current knowledge about pooled plasma, solvent detergent treated, x The current review considers the characteristics of the three products (Table 1), the theoretical risks associated with each product (Table 2), elements required for a rational decision, and a pragmatic approach to the prescription of plasma products (Table 3).

Blood Safety in the New Millennium

Edited by Susan L. Stramer, 236 pp, with illus, Bethesda, Md, American Association of Blood Banks, 2001.Blood Safety in the New Millennium, edited by Susan L. Stramer, is a multiauthored book that keeps a relatively uniform style for each of its 8 chapters. As stated in the foreword, “the book explores how far we have come in protecting the blood supply from transfusion-transmitted disease and projects what lies ahead.” The editor did an excellent job in successfully reaching this goal while keeping a somewhat consistent format.The first chapter on donor qualification focuses on the importance of behavioral science input into the donor-interviewing process and gives a brief overview of research tools that have improved or may improve donor screening, including a brief description of computer-assisted donor screening interviews.Chapters 2 and 3 are devoted to viral and parasitic agents threatening blood safety. The dynamics of viremia and parasitemia are discussed in a very practical way and are indicative of the era in which we live, acknowledging that the economic component plays an important role. The information and tables are up-to-date and appropriately used.Subsequent chapters cover a variety of issues. Chapter 4 complements the preceding 2 chapters by providing up-to-date information on emerging diseases that affect or may affect the blood supply. Chapter 5 provides a detailed, albeit sometimes redundant, look at the safety of the blood supply during the past 30 years. Chapter 6 returns to the topic of hepatitis C virus with an excellent description of this viral infection and its clinical consequences. Chapter 7 discusses cell-associated infections and cancer, including information on transfusion-related immunomodulation. The final chapter focuses on the medical decision dilemma of blood bankers and transfusion medicine specialists trying to find a balance between optimal blood safety and costs.This book is a well-written, up-to-date publication, which will capture the attention of blood bank medical directors, transfusion specialists, and pathology and clinical colleagues involved in decision-making processes to ensure a safe blood supply.

The quest for quality blood banking program in the new millennium the American way.

For an industry to succeed and satisfy its customers, "QUALITY" must be a primary goal. Quality has been central to blood banking from its inception, with the evolution of a Quality Program since the opening of the first blood bank in U.S. at the Cook County Hospital in 1937. Over the ensuing decades, continuous scientific progress in blood preservation, filters, viral and blood group testing, crossmatching, automation, and computerization including bar coding, etc. has contributed to the quality and safety of the blood products and transfusion service. However, with the advent of the AIDS era, an increasingly sensitized and informed public is continuously demanding that the highest level of quality be achieved and maintained in all processes involved in providing all blood products. The Food and Drug Administration (FDA) introduced the concept of a "zero risk blood supply" as the industry goal. Furthermore, the cost containment and resource-constrained environment have changed the complexity of the quality practice. Both regulatory agencies such as the FDA, the Health Care Financing Administration [HCFA, which was recently renamed as the Centers for Medicare and Medicaid Services (CMS) in July, 2001], and the State Department of Health, and accrediting agencies, such as the American Association of Blood Banks (AABB), the College of American Pathologists (CAP), and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), require blood banks and transfusion services to establish and follow a Quality Control and Quality Assurance Program for their licensing, certification and accreditation. Every laboratory has to comply with the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) quality requirements being implemented by the CMS. The FDA guidelines assist facilities in compliance with Current Good Manufacturing Practices (cGMP). The AABB's Quality System Essentials (QSE) are based on these specifications and provide additional guidance in implementing practices that assure quality and compliance with cGMP. AABB and CAP are granted "deemed status" as accrediting organizations under the CLIA '88 program by CMS, as well as JCAHO and some states. The International Standards Organization (ISO) has established international standards in most fields. The U.S. is represented in ISO by the American National Standards Institute (ANSI), and the National Committee for Clinical Laboratory Standards (NCCLS), as a global organization headquartered in the U.S., is a member of ANSI. The FDA and the AABB had begun incorporating many ISO principles into their own regulations and standards. The AABB's 10 QSEs are rooted in the 20 clauses of ISO 9000 series and compatible with their standards. In a Maslow-type model quality hierarchy by Tsiakals, so far the bottom three of the five progressive levels, Quality Control for method control, Quality Assurance for process control, and Quality System for system control have been implemented just to meet the regulatory and accrediting requirements. The next higher level, Quality Management for financial control, and the ultimate highest level, Total Quality Management for strategic control, should be our quest in this new millennium, and with the help of the AABB, ISO, FDA and all other organizations, we will achieve it. We should change our approach to quality issues from detection to prevention. We should improve the quality in transfusion practice itself by effective utilization of blood as a therapeutic resource with clear indication, maximum surgical blood order schedule, alternative transfusion such as autologous transfusion, hemodilution, and intra/post-operative blood salvage, surgical hemostasis, pharmacological hemostasis, and synthetic erythropoietin. Most importantly, implementation of the Quality Program should be something that we want to do rather than simply a burden that we have to do. A well-managed Quality Program is an effective and cost-efficient operation for the blood banks and transfusion services, and will enable us to better serve the patients for whom we exist.

Development of hematopoietic stem cell standards

Hematopoietic stem cell (HSC) transplantation is a promising therapy for cancer, leukemia, and a variety of non-malignant diseases. Standard-setting for this field has been spurred by increased availability of novel HSC sources (e.g., umbilical cord blood from unrelated donors), increasing complexity of laboratory processes used to manipulate the graft, heightened awareness of infectious disease transmission by biologic products, increased recognition by third-party payers of HSC transplantation as a covered health benefit, and growing emphasis on quality improvement programs in health care. Many aspects of HSC transplantation are now subject to regulatory oversight by the US Food and Drug Administration (FDA). In 1997, the FDA published “A proposed approach to the regulation of cellular and tissue-based products” (Fed Regist 1997;62:9721), which outlined a graded approach to regulation based on risk to the recipient of a particular tissue source and its intended use. For HPC products from autologous or related donor sources that are “minimally manipulated”, regulatory requirements would consist of facility registration and listing of products with the FDA, and certification that the facility meets professional standards. More extensively manipulated products and those from unrelated donors would be subject to more stringent requirements, including use of the investigational new drug (IND) or biologics license application (BLA) mechanism for product licensure. The two professional organizations in the US most engaged in development of standards and accreditation for HSC transplantation are the American Association of Blood Banks (AABB) and the Foundation for the Accreditation of Hematopoietic Cell Therapy (FAHCT). AABB's HSC standards were first published in 1991 as part of the 14th edition of the Standards for Blood Banks and Transfusion Services but were later developed in 1996 as a freestanding volume. In 2000, the 2nd edition of those standards were published as Standards for Hematopoietic Progenitor Cell Services, which presents a matrix of quality management and technical requirements based on the ISO 9000 approach. FAHCT's Standards for Hematopoietic Progenitor Cell Collection, Processing, and Transplantation were also published in 1996, the product of combining the laboratory standards of the International Society of Hematotherapy and Graft Engineering (ISHAGE) with the clinical standards of the American Society of Bone Marrow Transplantation (ASBMT). Other than the inclusion of clinical transplantation requirements in FAHCT's standards and the ISO 9000 format of AABB's standards, the two sets of standards are fully compatible with regard to donor screening, collection, processing, storage, and distribution of HSC products. The National Marrow Donor Program (NMDP) began in 1987 to facilitate HSC transplantation between unrelated donor and recipient pairs, and immediately established a standards-setting and accreditation process applicable to all donor recruitment, collection, and transplant centers associated with the registry. While less elaborate than those of AABB and FAHCT with regard to laboratory processing, NMDP standards emphasize requirements for donor screening and certification of expertise in the transplant center.

Discrepancies in Rh(D) typing of sensitized red blood cells using monoclonal/polyclonal anti-D reagents: case report and review

Abstract Instructions included with monoclonal Rh(D) typing reagents do not require routine use of an Rh control as immunoglobulin-coated red blood cells (RBCs) rarely yield falsely positive results with low protein reagents. However, the American Association of Blood Banks (AABB) Technical Manual recommends a concurrent control be performed on patients’ RBCs that type as group AB, D+. Proficiency testing surveys presented sensitized AB, D– RBCs, which resulted in a positive direct antiglobulin test and, in some samples, spontaneous agglutination in saline. One intent of the surveys was to monitor the accuracy of the reported Rh(D) type. On an initial survey, 19 of 115 (16.5%) participants reported the RBCs as D+. Of these laboratories, 63.2 percent (12/19) had used a monoclonal/ polyclonal blend anti-D reagent. On a subsequent survey, after educational material had been distributed, only five of 113 (4.4%) participants reported the Rh type as D+. Two of these five laboratories had used a monoclonal/polyclonal blend anti-D reagent. As RBCs coated with immunoglobulin may give unreliable results with Rh typing reagents, laboratories should follow the guidelines of the AABB Technical Manual. An appropriate control should be performed whenever RBCs from patients type as AB, D+. Immunohematology 2001;17:10–13.

Leukocyte-reduced blood transfusions: perioperative indications, adverse effects, and cost analysis.

Leukocyte-reduced blood transfusions: perioperative indications, adverse effects, and cost analysis.

Impact of molecular (DNA) testing on determination of parentage.

Abstract Objective.—To examine changes in parentage testing practices since the introduction of DNA polymorphisms. Methods.—Comparison of data from American Association of Blood Banks (AABB) annual questionnaires and the responses of participants to AABB–College of American Pathologists proficiency test panels. Results.—DNA polymorphisms have led to a complete change in the technical methods used by parentage testing laboratories. Conclusions.—The widespread use of DNA methods has increased the power of the information routinely provided to the courts in cases of disputed paternity, to agencies needing information about relatedness, and to the individuals who are tested.

Performance improvement in a hospital transfusion service.

Blood bankers have always embraced the concepts of quality exemplified by the American Association of Blood Banks' Standards for Blood Banks and Transfusion Services and its accreditation program. The emergence of a quality management system based on a set of quality system essentials represents a natural evolution of these quality initiatives. When fully implemented, a quality system provides a powerful tool with which to improve the quality of both intralaboratory and, importantly, extralaboratory processes related to transfusion medicine. In addition, a functional quality system enhances a transfusion service's ability to meet current and proposed requirements of the American Association of Blood Banks, the Food and Drug Administration, the Joint Commission on Accreditation of Healthcare Organizations, and the National Committee for Clinical Laboratory Standards.

Performance improvement in a hospital transfusion service.

Blood bankers have always embraced the concepts of quality exemplified by the American Association of Blood Banks' Standards for Blood Banks and Transfusion Services and its accreditation program. The emergence of a quality management system based on a set of quality system essentials represents a natural evolution of these quality initiatives. When fully implemented, a quality system provides a powerful tool with which to improve the quality of both intralaboratory and, importantly, extralaboratory processes related to transfusion medicine. In addition, a functional quality system enhances a transfusion service's ability to meet current and proposed requirements of the American Association of Blood Banks, the Food and Drug Administration, the Joint Commission on Accreditation of Healthcare Organizations, and the National Committee for Clinical Laboratory Standards.

Tissue engineering: the design and fabrication of living replacement devices for surgical reconstruction and transplantation

All procedures that restore missing tissue in patients require some type of replacement structure for the area of defect or injury. This form of therapy accounts for a large part of health-care resources (table). These devices have traditionally been totally artificial substitutes (joints), non-living processed tissue (heart valves), or tissue taken from another site from the patients themselves or from other patients (transplantation).1 Now a new alternative, tissue engineering, is becoming available to clinicians: the replacement of living tissue with living tissue that is designed and constructed to meet the needs of each individual patient. Tissue engineering is an interdisciplinary field which applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function, z Examples of tissue engineering can be found as early as 1933 when Bisceglie 3 encased mouse tumour cells in a polymer membrane and inserted them into the abdominal cavity of a pig. 3 The cells lived long enough to show that they were not killed by the immune system. In 1975, Chick and colleagues 4 reported their results of encapsulating pancreatic-islet cells in semipermeable membranes to aid glucose control in patients with diabetes mellitus. Replacement of the skin with cells in collagen gels, or collagen-glycosaminoglycan composites to guide regeneration, was attempted by the early 1980s and these techniques are now in clinical use. 5'6 The next major advance came with the recognition that thicker three-dimensional systems could organise implanted cells to form vascularised tissue in vivo. Synthetic degradable polymers were used as templates for cells to form permanent new tissues. 7 Systems were designed with highly porous structures to meet the needs for the mass transfer of large numbers of cells. Angiogenesis after implantation produced permanent vascularised new tissue. With the demonstration of experimental success in many different tissues, and the engineering flexibility that synthetic materials provided, tissue engineering has now gained wide attention. 2'8 A recent survey of tissue engineering as an emerging industry found that the total capital value of companies in the industry exceeded US$3.5 billion, that the industry growth rate was 22.5% per year, and that it employed over 2500 scientists with an annual expenditure of $450 million3 It has been estimated that the total market potential of tissue-engineered products in the USA alone is $80 billion annually (Business Week, July 27, 1998, p 61).