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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Phenotypic differences between CD34 positive cells in various transplantation tissues].

Transplantations to restore the hematopoietic system were originally performed with cells from the bone marrow (BM) (20) which was considered the only cell source comprising repopulating progenitor cells. The discovery that chemotherapy induced the mobilization of CD34+ cells into the peripheral blood (PB) (14) gave rise to the successful autologous transplantation of PBSC (1, 13). Also cord blood (CB) was found to contain considerable numbers of "stem cells", and to date at least 42 allogeneic transplantations have been performed with this cell source (22, J. Wagner, personal communication). Further investigations led to the successful autologous transplantation of positively selected CD34+ cells from BM and PB (18), and the latest results indicate that it is promising to transplant purified CD34+ cells obtained from cytokine-stimulated donors (4, 10, 15-16). Despite such achievements it remains unclear how many "stem cells" are required per kg of the recipient and how they are phenotypically characterized. In this communication we give examples of typical differences observed by flow cytometry and clonogenic assay between the CD34+ cells contained in the different cell sources. They may explain why it is not sufficient only to analyze the CD34+ cell populations which may represent progenitors of different lineages as well as of various states of differentiation. CB CD34+ cells are early myeloid progenitor cells with the highest incidence of CFU-mix among the three cell sources. They have a high proliferative potential in vitro. They hardly coexpress B cell antigens and they are partially negative for CD38.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Neurotransmitter receptors in fetal tissue transplants: expression and functional significance.

Numerous studies have examined receptor expression in neural transplants and their possible role in transplant-induced functional recovery from lesion-induced deficits. Herein we attempt to summarize the results of these studies, especially those from studies involving striatal transplants. Autoradiographic studies indicate that dopamine D1 and D2, muscarinic, cholinergic, 5-HT2, opiate mu, beta adrenergic and cholecystokinin (CCK) receptors are present in striatal transplants. Many of these receptors are present regardless of the transplant location and surrounding environment. This suggests that the expression of these receptors is determined by intrinsic properties of transplanted tissue, and is independent of transplant location and environment. Some transplant receptors, such as dopamine D1 and D2 and muscarinic receptors in striatal transplants, or 5-HT2 receptors in cortical transplants, display a patchy distribution which is dissimilar to that in the corresponding adult host tissue. This manuscript discusses this "abnormal" receptor distribution and possible explanations. Electrophysiological studies have indicated that some of the transplant receptors respond to physiological and pharmacological stimulation, suggesting that they are functional. However, the association of receptor expression with behavioral recovery is uncertain. The expression of neurotransmitter receptors in neural transplants may not be essential for the functional recovery associated with trophic mechanisms. However, neurotransmitter receptors may play an important role when functional recovery requires neuroanatomical integration between the host brain and the transplanted tissue.

Animals↗
PubMed1986

Irradiation of free vascularized tissue transplants in rats.

The aim of this experimental investigation was to show whether immediate irradiation of a free flap or an island flap is dangerous or not. The free epigastric flap of the rat was used as a model for this investigation. The patency of the epigastric vessels of the rat was not influenced by the irradiation and the histological findings showed no early reaction to the irradiation of the vessels of the transplanted tissue. The vessels of this experiment indicate that a free tissue transplantation is possible even if a combined radio-surgical treatment is planned.

Animals↗
PubMed1991

The cutting edge: neurotransmitters and brain tissue transplant.

Neural tissue transplant represents one of the most exciting and controversial areas of current basic neuroscience research. It offers enormous therapeutic promise for patients with degenerative and traumatic neurologic disorders. This article reviews the functions of several common neurotransmitters and examines the clinical applications of tissue transplant into the human nervous system.

Animals↗
PubMed1992

Autoradiographic determination of glucose content and estimation of the lumped constant in intracerebral neuronal tissue transplants.

The quasi-steady-state distribution volume of brain glucose was measured using 3-O-[14C]methylglucose quantitative autoradiography in a group of rats (n = 5) which 12-15 weeks previously had undergone unilateral ibotenic acid-induced lesion of the nucleus basalis magnocellularis, followed by implantation into ipsilateral neocortex of primordial basal forebrain cell suspensions. The effects of the lesion and the presence of transplanted tissue in neocortex were visualized by acetylcholinesterase histochemistry. The 3-O-[14C]methylglucose tracer was distributed homogeneously throughout the host brain areas analysed, with no side-to-side differences, despite a marked unilateral depletion of acetylcholinesterase activity ipsilateral to the lesion site. Whilst the transplants were indistinguishable from the homogeneity of surrounding host frontal cortex, there was a 70% increase in the apparent distribution volume of methylglucose localized around the ibotenate injection site and associated needle tract. Brain glucose content is an important experimental variable affecting the lumped constant of the 2-deoxyglucose technique. There was no evidence of any significant difference in the lumped constant between transplant and host tissue which might compromise the validity of the 2-deoxyglucose technique when used together with intracerebral implantation of fetal neuronal cell suspensions.

3-O-Methylglucose↗
PubMed1993

[Malignant tumor developing in transplanted tissue in the oral cavity (case report)].

Primary and metastatic malignant tumors appears frequently in the head and neck region. The occurrence of malignancies in tissues--transplanted to this area--are extraordinary rare. Authors report about a case, where the tumor developed in a cylindroid jump flap, used to the closure of the cleft palate. They discuss theoretical aspects, as well as the course of the disease.

Adult↗
PubMed1986

A comparative study of transplant sites for endocrine tissue transplantation in the pig.

Thyroid and thymus tissue autografts were used to examine the suitability of different transplant sites in the pig for endocrine tissue transplantation. The omental pouch, gall bladder fossa and renal subcapsular space showed optimal implantation, preservation and vascularisation of graft tissue. Marked dissemination of graft tissue was observed at intramuscular sites and graft viability at subcutaneous sites in the ear was poor. The omental pouch represents a potentially suitable site for pancreatic islet tissue transplantation studies in the pig.

Animals↗
PubMed1995

Free tissue transplantation in the 90's.

Free tissue transplantation is now a well-established discipline and a common phrase in the medical literature. Only as recent as two decades ago, free tissue transplantation with microvascular anastomosis was a daring venture attempted by a selected few. It was considered to be a heroic effort of last resort when other reconstructive options were exhausted. Reconstructive surgeons were limited by tissue availability before free tissue transplantation with microsurgical techniques. With pedicle flaps, patients were subjected to multiple operations and hospitalizations and long periods of immobilization. The possibility of moving a large block of tissue to another body location by anastomosing its vascular pedicle with local blood vessels was tantalizing to reconstructive surgeons. The ability to perform anastomosis on small vessels had to be mastered before such a dream could be realized.

Amputation, Traumatic↗
PubMed1990

Ethical considerations in fetal tissue transplantation.

Recent research using fetal tissue transplants has expanded possible treatment options for several traumatic and degenerative neurologic disorders. However, the expectations of therapeutic benefit to be gained from these methods have been challenged by an equivalent degree of controversy. Fundamental viewpoints regarding abortion, physical autonomy and the principle of harm have been raised against continuing research and the use of fetal tissue transplants. In this article, we first attempt to elucidate the practice, potential and limitations of such techniques. The critical, yet unresolved issues of supply and sources of fetal tissue are also discussed. In light of these concepts, we examine certain pertinent obligations and ethical concerns that may clarify the nurses' role in dealing with cases involving the use of fetal tissue transplants.

Abortion, Legal↗
PubMed1987

Patterns of angiogenesis in neural transplant models: I. Autonomic tissue transplants.

Functional vascular connections must form rapidly to prevent ischemic damage to grafted neural tissues. The temporal sequence by which transplant circulation is re-established provides information about the angiogenic capacity of either intact or damaged CNS blood vessels. This study compares the time course and mechanism of vascular reperfusion in allografts of superior cervical ganglia or adrenal medulla inserted either into the fourth ventricle or directly into the parietal cortex of perinatal rats. Tritiated thymidine was administered to recipients to determine angiogenic patterns at various postoperative time periods. After processing for light microscopic autoradiography, host and graft endothelial labelling indices were determined in order to establish the temporal sequence and location of vascular proliferation. Correlative electron microscopy depicted the morphological changes in transplant vasculature. Some recipients were prelabelled with 3H thymidine prior to transplantation to determine if host vessels invaded the grafts. Intraventricular graft vessels initially collapsed but sustained minimal ischemic damage and were completely reperfused by 24 hours postoperative. Adjacent intact host vessels attained peak 3H thymidine incorporation at 20 hours. Intrinsic graft vessels were radioactively labelled only after 48 hours. Intraparenchymal transplants surrounded by minimal trauma exhibited a similar temporal sequence of reperfusion and host endothelial proliferation. Intrinsic graft vessels in intraparenchymal grafts sustained more severe damage. With increased trauma, a concomitant delay in graft reperfusion time was observed. Grafts within prelabelled hosts rarely contained any labelled endothelium, indicating that anastomotic connections were made between original, intrinsic graft vessels and nearby host vascular sprouts. This study demonstrates that mature autonomic tissue stimulates the growth of adjacent host vessels when transplanted to undamaged brain surfaces. The anastomosis of nascent host vessels with pre-existing graft vessels is responsible for the rapid re-establishment of circulation within the transplants. A similar mechanism occurs within intraparenchymal grafts, although the rapidity of reperfusion appears to be predicated on the amount of trauma present at the graft site.

Adrenal Medulla↗
PubMed1993

Extracorporeal circulation for tissue transplantation (in the case of venous flaps).

During free-tissue transplantation, recipient vessels are often crushed as a result of trauma or radiation therapy, making anastomosis of vessels difficult. In some cases, a second operation is unavoidable because of formation of a postoperative thrombus at sites of the anastomosis. To solve such problems, it should be possible to transplant tissue anywhere in the body without vascular anastomosis by extracorporeal circulation. This study mainly concerned venous flaps that were spindle-shaped and 4 x 3 cm in size. One hundred and forty-six male Japanese White rabbits, weighing 2.0 to 2.5 kg, were used. Stabilized hemoglobin, lactated Ringer's solution, whole blood, and plasma were used as perfusate. Each of these perfusates was injected at a rate of 5 ml per hour continuously for 3 days in good recipient sites and for 7 days in poor recipient sites. Five rabbits were used in each group. The flaps were examined histologically and electron microscopically. Moreover, in the plasma group, microangiography was performed to observe blood circulation between the flap and the surrounding tissue. The flaps survived in all cases in which the plasma group had good recipient beds but did not survive in any of the other cases, in which degeneration of the endothelial cells was detected prior to edema. According to the results of this examination, tissue viability of the venous flap could be maintained for at least 3 days by perfusion of plasma. During this time, in the cases of good recipient sites, blood may begin to recirculate between the flap and the surrounding tissue.

Angiography↗
PubMed1985

Late patency of clinical microvascular anastomoses to free composite tissue transplants. II. Hemodynamical aspects.

In a series of 37 free composite tissue transplantations performed to the lower extremity in 34 patients, skin islands were included in 35 cases, as a cutaneous island flap (3), as a musculocutaneous island flap (19), and as an osteocutaneous island flap (13). In a follow-up study which included 26 patients with 29 flaps 6-48 months postoperatively an estimate was made of the importance of the blood supply through the vascular pedicle relative to the collateral blood supply through the recipient bed. Using transcutaneous oxygen tension measurements a significant reduction in calculated relative skin blood flow averaging 70% (p much less than 0.01) was seen after digital occlusion of the vascular stalk, suggesting that patent microvascular anastomoses are important for the vascularity of the transplanted tissues, not only for immediate postoperative survival, but also on the longer view.

Adolescent↗
PubMed1981

The brain and subarachnoid space as possible sites for endocrine tissue transplantation.

Immunological rejection has been the major problem limiting the successful transplantation of tissue from one animal to another. Recent technological developments, combined with the use of the central nervous system as an immunologically privileged site, suggest that it might be possible to achieve long-term survival of hormone-secreting tissues, between two gentically dissimilar animals, if these tissues are transplanted to the brain and subarachnoid space of the host. The physiological parameters that should be considered in the clinical application of a transplant of this type are discussed.

Animals↗
PubMed1993

[Microsurgical tissue transplantation in the treatment of recurrent basaliomas of the head].

The authors analyse their experience in the use of microsurgical transplantation of tissues in the management of recurrent basaliomas of the head in 20 patients. Various types of autografts were used, such as: the greater omentum, thoracodorsal, inguinal, scapular, deltoid, and radius grafts. The results were good in most cases. It is claimed that microsurgical autotransplantation of tissue complexes is a necessary component in the treatment of severe forms of basaliomas of the skin of the head.

Adult↗