Tissue Engineering; Current Status & Futuristic Scope.

Almost 30 years have passed since the term 'tissue engineering' was created to represent a new concept that focuses on the regeneration of neotissues from cells with the support of biomaterials and growth factors. This interdisciplinary engineering has attracted much attention as a new therapeutic means that may overcome the drawbacks involved in the current artificial organs and organ transplantation that have also been aiming at replacing lost or severely damaged tissues or organs. However, the tissues regenerated by tissue engineering and widely applied to patients are still minimal, including skin, bone, cartilage, capillary, and periodontal tissues. What are the reasons for such slow advances in clinical applications of tissue engineering? This article gives a brief overview of the current state of tissue engineering, covering the fundamentals and applications. The fundamentals of tissue engineering involve cell sources, scaffolds for cell expansion and differentiation, as well as carriers for growth factors. Animal and human trials are a major part of the applications. Based on these results, some critical problems to be resolved for the advances of tissue engineering are addressed from the engineering point of view, emphasizing the close collaboration between medical doctors and biomaterials scientists.

Study of Single Donor Platelet (SDP) Preparation by Baxter CS 3000 plus and Haemonetics MCS plus.

BACKGROUND: In plateletpheresis blood is withdrawn from a donor in anticoagulant solution and separated into components. Platelets are retained and the remaining components are returned to the individual. METHODS: The present study was aimed to compare the platelet yield and collection efficiency of Baxter CS 3000 plus and Haemonetics MCS plus cell separators and to study adverse donor reactions. Donors were selected as per the set criteria for single donor platelet (SDP) preparation. Donors' samples for pre donation and post donation platelet count were collected in EDTA and for product counts in the sample pouch attached with apheresis kits. The results were obtained by haematology analyzer. Platelet yield and collection efficiency were calculated. RESULT: Results were tabulated for both the cell separators and analyzed. Platelet yield was marginally better with Baxter CS 3000 plus but collection efficiency was better with the Haemonetics MCS plus. Residual white cells were more in single donor platelet concentrate preparation by MCS plus. Adverse donor reactions were similar with both cell separators, in form of mild citrate toxicity and mild to moderate pain at phlebotomy site. CONCLUSION: Findings of the present study along with other factors such as less priming time for kit, portability of cell separator, better patient comfort owing to single arm venous access and lesser cost suggest that Haemonetics MCS plus is a better choice as compared to Baxter CS 3000 plus cell separator.

Comparative Study of Blood Cross Matching Using Conventional Tube and Gel Method.

BACKGROUND: Conventionally tube method is used for compatibility and cross matching in transfusion medicine. METHODS: A comparative study was carried out to evaluate the efficacy of conventional tube and gel technique. RESULT: Compatibility testing was performed on 1000 blood samples by conventional test tube method and DiaMed gel method. The results were analysed. CONCLUSION: The gel method was found to be a rapid and reliable procedure without controls. There was no requirement of wash phase in indirect antiglobulin test and sensitivity and specificity was comparable to spin tube method. We conclude that this technique is a better substitute for spin tube method.

Comparison of CD4 and CD8 lymphocyte counts in HIV-negative pulmonary TB patients with those in normal blood donors and the effect of antitubercular treatment: hospital-based flow cytometric study.

BACKGROUND: This study was designed to flow cytometrically determine baseline and sequential values of CD4 and CD8 lymphocyte subsets in patients without the human immunodeficiency virus and with pulmonary tuberculosis (TB) and to correlate these values with those obtained from normal male blood donors and with the radiologic extent of disease and response to therapy. METHODS: We studied 39 male patients without the human immunodeficiency virus and with sputum positive for pulmonary TB who had been admitted to Military Hospital (Cardiothoracic Center) in Pune, India. Clinical, laboratory, and radiologic evaluations of these patients were done. Hematologic parameters were assessed by an automated hematology cell counter (AcT*Diff, Coulter), and T-cell subsets (CD4 and CD8) were determined flow cytometrically (EPICS-XL, Coulter). RESULTS: CD4 counts and percentages of CD4 were significantly lower, but CD8 values were normal, in patients with pulmonary TB when compared with values obtained in normal blood donors. The CD4/CD8 ratio was significantly lower in patients with TB. The CD4 counts normalized with antitubercular treatment. The radiologic extent of disease did not correlate well with the immune parameters studied. CONCLUSIONS: TB is a reversible cause of CD4 lymphocytopenia and is associated with normal numbers of CD8 cells. The radiologic extent of disease does not seem to determine the immune response.

Should one vaccinate patients with chronic liver disease for hepatitis A virus in India?

BACKGROUND: Hepatitis A virus (HAV) vaccination is recommended worldwide for patients with chronic liver disease to prevent decompensation due to superinfection with HAV. India being endemic for HAV, the prevalence of pre-existing antibodies against HAV due to subclinical exposure to the virus in childhood among patients with chronic liver disease may be high and, therefore, vaccination may not be needed. However, little data are available on the prevalence of HAV antibody among patients with chronic liver disease in India. METHODS: All patients with chronic liver disease seen at Gastroenterology Center, Army Hospital R and R, New Delhi during the year 2002 and diagnosed to have either chronic liver disease were tested for the presence of IgG anti-HAV antibody in their sera (using a commercial ELISA kit). All patients with acute exacerbation or rapid deterioration of a preexisting chronic liver disease were separately studied for presence of IgM anti-HAV. In addition, a matched number of patients who attended the center due to diseases other than liver disease were also studied as controls. RESULTS: One hundred and eighty seven patients of chronic liver disease and 89 controls were studied. Mean age of these two groups was 38.6 and 42.1 years and 153 (81.8%) and 78 (87.6%) of them were males respectively. Etiology of chronic liver disease was HBV infection in 91(48.7%), HCV infection in 62 (33.2%), autoimmune chronic hepatitis in 3 (1.6%), PBC in seven (3.7%) and cryptogenic 24 (12.8%). Of these 179 (95.7%) patients tested positive for IgG anti-HAV. A total of 37 hospitalisations in 29 patients were noted during the study period due to acute exacerbation of pre-existing chronic liver disease. None of these were positive for IgM anti-HAV, while 28 were positive for IgG anti-HAV. Among the controls, 87 controls (94.6%) were positive IgG anti-HAV. The prevalence of anti-HAV positivity was similar among patients with various etiologies. CONCLUSION: Vaccination against HAV is not routinely required among patients with chronic liver disease in India as there is a very high prevalence of pre-existing antibodies in these patients. HAV superinfection as a cause of acute exacerbation of chronic liver disease was not seen in this.

Normal values of CD4 and CD8 lymphocyte subsets in healthy indian adults and the effects of sex, age, ethnicity, and smoking.

BACKGROUND: Information on lymphocyte populations (T, B, and natural killer cells) and subpopulations (CD4 and CD8) in India is generally lacking. Measurement of T-cell subsets is important in India for evaluating disease stage and progression in individuals with the human immunodeficiency virus (HIV). Hence, this study was conducted to provide normal ranges of absolute and percentage values of CD4 and CD8 T-lymphocyte subsets and the ratio of CD4 to CD8 in normal Indian adults. METHODS: Flow cytometric analysis (EPICS-XL) was used to determine the range of T-lymphocyte subpopulations in normal Indian blood donors at Command Hospital and the Armed Forces Medical College, Pune, India. The reference population consisted of 94 healthy HIV-seronegative blood donors. T-lymphocyte subsets were analyzed with two-color immunophenotyping of peripheral blood lymphocytes with the use of a lysed whole-blood technique and enumerated. RESULTS: For normal values of various blood components, we found mean values of 2114 cells/microl for total lymphocytes, 865 cells/microl (40.2%) for CD4(+) lymphocytes, 552 cells/microl (31.3%) for CD8(+) lymphocytes, and 1.7 for the CD4:CD8 ratio. The 95% confidence intervals for the same parameters were 1115-4009 cells/microl, 430-1740 cells/microl (30.75-49.60%), 218-1396 cells/microl (20.06-42.52%), and 0.39-3.02 respectively. Females had significantly higher CD4 counts (P < 0.05), percentage of CD4 lymphocytes (P < 0.01), and CD4:CD8 ratio (P < 0.01). Males had a significantly higher percentage of CD8 lymphocytes (P < 0.01). They also had higher CD8 counts that did not reach significance. Age, ethnicity (Dravidian versus Aryan), smoking, alcohol consumption, and the interval between drawing the blood sample and its analysis were factors that did not produce statistically significant differences in the T-cell subsets studied. CONCLUSIONS: When compared with other published series, the CD4 and CD8 values in healthy Indians were no different from those reported in the West. These observations have important clinical implications for the use of T-lymphocyte subset measurements in India, especially in the management of HIV infection. The normal ranges established by this study can be used as a reference for decisions made in clinical practice.

Artifical Blood.

Elimination of unwanted side-effects, especially transfusion-transmitted diseases (HIV and hepatitis) and leucocyte-mediated allosensitisation, is an important goal of modern transfusion medicine. The problems and high cost factor involved in collecting and storing human blood and the pending world-wide shortages are the other driving forces contributing towards the development of blood substitutes. Two major areas of research in this endeavour are haemoglobin-based oxygen carriers (HBOCs) and perfluorochemicals. Even though they do not qualify as perfect red blood cell substitutes, these 'oxygen carrying solutions' have many potential clinical and non clinical usages. These can reach tissues more easily than normal red cells and can deliver oxygen directly. These are not without adverse effects, and extensive clinical trials are being conducted to test their safety and efficacy. New understandings on the mode of action of these products will help to define their utility and application. Only after successful clinical trials can they be used for patient management, after approval by the FDA.

Collection, Separation, Enumeration and Cryopreservation of Umbilical Cord Blood Haematopoietic Stem Cells - An Experimental Study.

Cord blood as a source of haematopoietic stem cells (HSC) has several advantages as it is easily available, involves non-invasive collection procedure and is better tolerated across the HLA barrier. Since the first cord blood transplant in 1988, over 1000 cord blood HSC transplants have been done world wide. The present study was carried out for collection, separation, enumeration and cryopreservation of cord blood HSC. 30 samples of cord blood HSC were collected after delivery of infant prior to expulsion of placenta. The average cord blood volume collected was 101.33ml. Mononuclear cell count ranged from 7.36 to 25.6 × 10(7) ml. Viability count of mononuclear cells was 98.4%. After 6 months of cryopreservation, the viability count on revival was over 82.1%.

Cord blood stem cell banking and transplantation.

Stem cells have the ability to divide for indefinite periods in culture and to give rise to specialized cells. Cord blood as a source of hematopoietic stem cells (HSC) has several advantages as it is easily available, involves non-invasive collection procedure and is better tolerated across the HLA barrier. Since the first cord blood transplant in 1988, over 2500 cord blood HSC transplants have been done world wide. Since then, the advantages of cord blood as a source of hematopietic stem cells for transplantation have become clear. Firstly, the proliferative capacity of HSC in cord blood is superior to that of cells in bone marrow or blood from adults. A 100 ml unit of cord blood contains 1/10th the number of nucleated cells and progenitor cells (CD34+ cells) present in 1000 ml of bone marrow, but because they proliferate rapidly, the stem cell in a single unit of cord blood can reconstitute the entire haematopoietic system. Secondly, the use of cord blood reduces the risk of graft vs host disease. Cord Blood Stem Cell banks have been established in Europe and United States to supply HSC for related and unrelated donors. Currently, more than 65,000 units are available and more than 2500 patients have received transplants of cord blood. Results in children have clearly shown that the number of nucleated cells in the infused cord blood influences the speed of recovery of neutrophils and platelets after myeloablative chemotherapy. The optimal dose is about 2 x 10(7) nucleated cells/kg of body weight. The present study was carried out for collection, separation, enumeration and cryopreservation of cord blood HSC and establishing a Cord Blood HSC Bank. 172 samples of cord blood HSC were collected after delivery of infant prior to expulsion of placenta. The average cord blood volume collected was 101.20 ml. Mononuclear cell count ranged from 7.36 to 25.6 x 10(7)/ml. Viability count of mononuclear cells was 98.1%. After 1 year of cryopreservation, the viability count on revival was over 82.1%. Related cord blood stem cell transplantation was carried out in three cases at Army Hospital (R&R), Delhi Cantt.

TRANSFUSION REACTIONS: AFMC EXPERIENCE.

Transfusions of blood and its components are useful and lifesaving. Adverse effects occur during or after transfusion, called hazards or complications of blood transfusion. Complications/hazards of various types which occurred in the patients following transfusion of blood/blood components in Armed Forces Hospitals of Pune-Kirkee complex were analysed with relevant investigations. Out of a total number of 13,039 transfusions of blood and blood components from 01 June 1995 to 31 July 1997, there were 104 (0.8%) adverse reactions. Non haemolytic febrile transfusion reaction was the commonest seen in 73 (70.2%) transfusions, followed by allergic reactions in 19 (18.3%) cases. Nonspecific reactions were seen in 11 (10.6%). One haemolytic transfusion reaction occurred due to wrong labelling of blood sample received from the ward for compatibility testing. There were no fatalities.

PREVALENCE OF HEPATITIS C VIRUS ANTIBODY IN HETEROGENEOUS POPULATION OF BLOOD DONORS.

The transfusion of blood and blood products exposes recipients to both infectious and non-infectious adverse effects. Information on HCV infection in India is still sketchy. Data on small numbers of volunteer including replacement blood donors tested by ELISA has shown rates of 0.2-4%. 6602 volunteer including replacement blood donors reported to the Department of Transfusion Medicine, Armed Forces Medical College, Pune with effect from 01 September 97 to 31 July 98. Screening for anti-HCV antibody was done by third generation ELISA kits. 29 donors were positive for anti-HCV antibody. The prevalence rate of HCV infection is 0.44% which compares with the studies from other centres. The prevalence rate was higher in the replacement donors as compared to voluntary donors. There is a need to include anti-HCV to the list of mandatory tests for screening of blood donors.

AUTOLOGOUS TRANSFUSION AFMC EXPERIENCE (1992-1996).

In this era of Acquired Immune Deficiency Syndrome (AIDS) and other infectious diseases - complications of homologous blood transfusion, autologous transfusion is the safest possible blood for transfusion. The present study was conducted from January 1992 to August 1996 to analyse the programme of autologous transfusion. A total of 471 pre-operative autologous collections were undertaken out of a total of 27,542 blood collections during this period. The present study shows a significant increase in autologous collections from 0.44 per cent in 1992 to 3.94 per cent till August 1996. 37.1 per cent autologous donors were from the urosurgery ward. Of the total 471 autologous blood units collected, 171 were transfused to the autologous donors (27.5%).

STUDY OF WEAK D PHENOTYPE IN HETEROGENEOUS POPULATION.

Weak D is the current phenotypic term used to denote a weakened expression of Rhesus (Rh) D antigen on red cells due to a quantitative or qualitative difference in Rh antigen. The present study was undertaken from January 1986 to August 1997. Out of a total of 5042 Rh D confirmation tests 22 (0.43%) weak D phenotypes were detected. Fifteen (68.3%) weak D phenotypes were from blood group O. Five (22.7%) from blood group A and one (4.5%) each from blood group B and AB. There were 15 males and 7 females. There were no cases of haemolytic disease of the newborn or Rh incompatibility.