Multicystic, heterogeneously enhancing meningioma in an octogenerian.

A multicystic meningioma in an octogenerian whose tissue diagnosis was ill-defined and misleading on preoperative neuroradiologic imaging is presented. Nauta has described four cyst types that can develop in cystic meningiomas. We report the first case in which three cyst types are demonstrated concurrently, describe the histopathology and surgical management. This case represents a rare variant of a common tumour in an unusual age group, and underscores the need for definitive biopsy and resection as indicated. Furthermore, the diagnosis of multicystic meningioma does not favour an aggressive histopathology in this case.

Incipient erosion of biostabilized sediments examined using particle-field optical holography.

Laser holography allows images of three-dimensional space at ultra-high resolution to be recorded onto photographic plates. Recorded scenes can be "replayed" with a second laser beam into free space and optically "interrogated" using either a microscope or a camera by sequentially focusing on increasing distances from the hologram in the field of view (optical sectioning). From these sections, information on the relative locations and orientation in space of suspended particles as well as the morphology of particles can be obtained. This paper examines the utility of "in-line" laser holography to discriminate the size and the morphology of sand particles eroded under turbulent shear flow during benthic sediment transport. The influence of a commercially available adhesive polymer (xanthan gum, derived from the bacterium Xanthomonas campestris) on sediment stability and resuspended particle morphology is described. The major implications for carbon and sediment cycling within estuaries are highlighted.

Decellularized human valve allografts.

BACKGROUND: Variable performance of allograft tissues in children and some adults may be linked to an immune response and could be mitigated by reducing implant antigenicity. METHODS: As endothelial and fibroblast cells are the likely source of valve antigenicity, human (CryoValve SG) and sheep pulmonary valves were decellularized using the SynerGraft treatment process. Treated valves were evaluated in vitro using histochemical, biomechanical, and hydrodynamic methods, and compared with standard cryopreserved valves. Four SynerGraft-treated and two cryopreserved sheep pulmonary valves were implanted as root replacements in the right ventricular outflow tract of growing sheep and monitored echocardiographically and histologically at 3 and 6 months. CryoValve SG human pulmonary valves were implanted in 36 patients. RESULTS: SynerGraft treatment reduced tissue antigen expression but did not alter human valve biomechanics or strength. Decellularized sheep allograft valves were functional during the implantation period, and, they became progressively recellularized with recipient cells. In humans, CryoValve SG pulmonary valves did not provoke a panel reactive antibody response. CONCLUSIONS: SynerGraft decellularization leaves the physical properties of valves unaltered and substantially diminishes antigen content. Reduction in implant cellularity enables host recellularization of the matrix, which should favorably impact long-term graft durability.

Transformation of nonvascular acellular tissue matrices into durable vascular conduits.

BACKGROUND: Prosthetic grafts commonly used for vascular reconstruction are limited to synthetics and cross-linked tissue grafts. Within these devices, graft infections are common, compliance mismatch is significant, and handling qualities are poor. Natural biological tissues that are unfixed have been shown to resist infections and be durable and compliant. A natural biological matrix that could be remodeled appropriately after implantation would be a desirable graft for vascular reconstruction. METHODS: SynerGraft tissue engineering strategies have been used to minimize antigenicity and produce stable unfixed vascular grafts from nonvascular bovine tissues. These grafts have replaced the abdominal aortas of 8 dogs that have been followed for up to 10 months. RESULTS: Early evaluation indicates rapid recellularization by recipient smooth muscle actin positive cells, which become arranged circumferentially, into the media. Arterioles were present in the adventitial areas and endothelial cells were seen to cover lumenal surfaces. After 10 months, grafts were patent and not aneurysmal. CONCLUSIONS: These data indicate that SynerGraft processing of animal tissues is capable of producing stable vascular conduits that exhibit long-term functionality in other species.

Recellularization of heart valve grafts by a process of adaptive remodeling.

The objective of this study was to investigate if function and durability of connective tissue grafts stems from in vivo revascularization and recellularization. Viability is important for durable valve performance, demonstrated by pulmonary autografts. A pattern of in vivo recellularization occurs in xenogeneic or allogeneic heart valves decellularized prior to implantation, dictated by the tissue matrix and functional biomechanics. Porcine or sheep heart valves were decellularized with the SynerGraft antigen reduction process (a common treatment process to remove all histologically demonstrable leaflet cells), and implanted as pulmonary (n = 11) or aortic valve (n = 9) replacements in sheep. Sheep allograft pulmonary valves (n = 4) were implanted as pulmonary valve replacements. Recellularization was evaluated histologically after 3, 4, 5, 6, and 11 months, with cell phenotypes identified using specific antibodies. SynerGraft heart valves were progressively recellularized beginning with an initial cellular infiltrate, and subsequent repopulation with mature interstitial cells. This process occurs in the conduit and then in the leaflet, and is associated with revascularization of the graft. Functional, fully developed fibrocytes, actively synthesizing type I procollagen (antibody probe) were present within 3 months. As the process matured cell density and distribution became similar to native valve leaflets with localization of smooth muscle actin positive cells at the ventricularis/spongiosa interface. After 11 months, leaflet explants had no detectable inflammatory cells, were as much as 80% repopulated, and had a distribution of smooth muscle actin positive cells similar to that of the natural leaflet. SynerGraft- treated heart valve implants are repopulated by a process typical of adaptive remodeling following implantation. This antigen reduction treatment is the first successful tissue engineering effort obtaining an implant with mature recipient cells capable of matrix protein synthesis. Normal early valve function and durability is maintained.

Site-specific immunosuppression: mechanisms of cellular immunosuppression that are operative at local and systemic levels.

The cellular mechanisms by which topical cyclosporine A (tCsA) induces site-specific immunosuppression were investigated. Experiments were designed to elucidate how cyclosporine A (CsA) suppresses activated immunocytes in animals that are undergoing local alloactivation and concomitant tCsA immune suppression. Lewis rats received dual Lewis x Brown Norway rat skin allografts; the rats were treated with systemic CsA (sCsA) at 8 mg/kg/day for 10 days after grafting and then tCsA and vehicle thereafter. CsA added to mixed lymphocyte reactions 24 hours after culture initiation modeled the local effects of CsA on alloactivated immunocytes, and tCsA in conjunction with limited sCsA prolonged local skin allograft survival. CsA inhibited both antigen-specific and nonspecific activated alloresponses of immunocytes from animals that had received allografts and that underwent limited sCsA treatment only in a dose-dependent manner. When tCsA had been applied, immunocyte responses to a nonspecific antigen were extremely CsA-resistant as compared with those induced by antigen-specific suppression. However, this nonspecific alloresponse was fully suppressible with the use of elevated CsA doses (66 microg/mL); thus alloresponding immunocytes were significantly more sensitive to CsA if they were challenged with the donor antigen and preexposed to limited sCsA followed by tCsA in vivo.

Transpecies heart valve transplant: advanced studies of a bioengineered xeno-autograft.

BACKGROUND: Tissue engineering approaches utilizing biomechanically suitable cell-conductive matrixes should extend xenograft heart valve performance, durability, and growth potential to an extent presently attained only by the pulmonary autograft. To test this hypothesis, we developed an acellular, unfixed porcine aortic valve-based construct. The performance of this valve has been evaluated in vitro under simulated aortic conditions, as a pulmonary valve replacement in sheep, and in aortic and pulmonary valve replacement in humans. METHODS: SynerGraft porcine heart valves (CryoLife Inc, Kennesaw, GA) were constructed from porcine noncoronary aortic valve cusp units consisting of aorta, noncoronary aortic leaflet, and attached anterior mitral leaflet (AML). After treatment to remove all histologically demonstrable leaflet cells and substantially reduce porcine cell-related immunoreactivity, three valve cusps were matched and sewn to form a symmetrical root utilizing the AML remnants as the inflow conduit. SynerGraft valves were evaluated by in vitro hydrodynamics, and by in vivo implants in the right ventricular outflow tract of weanling sheep for up to 336 days. Cryopreserved allograft valves served as control valves in both in vitro and in vivo evaluations. Valves were also implanted as aortic valve replacements in humans. RESULTS: In vitro pulsatile flow testing of the SynerGraft porcine valves demonstrated excellent valve function with large effective orifice areas and low gradients equivalent to a normal human aortic valve. Implants in sheep right ventricular outflow tracts showed stable leaflets with up to 80% of matrix recellularization with host fibroblasts and/or myofibroblasts, and with no leaflet calcification over 150 days, and minimal deposition at 336 days. Echocardiography studies showed normal hemodynamic performance during the implantation period. The human implants have proven functional for over 9 months. CONCLUSIONS: A unique heart valve construct has been engineered to achieve the equivalent of an autograft. Short-term durability of these novel implants demonstrates for the first time the possibility of an engineered autograft.

Composite tissue allografts in rats: IV. Graft-versus-host disease in recipients of vascularized bone marrow transplants.

This laboratory has used a composite tissue allograft model as a vehicle for studies on a new type of bone marrow transplant, the vascularized bone marrow transplant. The model consists of a rat hind limb transplant that incorporates integumentary musculoskeletal, and lymphopoietic tissues. These transplants, in comparison with conventional marrow transplants, have the advantage of providing a syngeneic microenvironment and immediate engraftment of both mature and progenitor hemopoietic cells at the time of transplantation. The characteristics of graft-versus-host disease were studied in this model. Lewis X Brown Norway F1 (LBN RT-1(1+n)) rats received hind limbs from Lewis (LEW RT-1(1)) donors (n = 19). Animals were observed daily for signs of graft-versus-host disease. Necropsies were performed. A minority of animals developed lethal disease (7 of 19 recipients) and demonstrated cachexia with concomitant histopathologic changes of the disease. Acute and chronic groups emerged with distinct clinical courses, which are similar to other models of this disease. Recipients of vascularized bone marrow transplants (limb transplants) showed clinical and histopathologic changes of the disease. The transplants may be used as a model of graft-versus-host disease in humans. Most interestingly, the transplant has a lower incidence of disease compared with other methods of bone marrow transplantation and represents an alternative to conventional bone marrow transplantation, which deserves further exploration. It may be possible to develop a new technique for bone marrow transplantation based on this surgical approach. It is proposed that the transfer of vascularized blocks of bone/marrow into prospective recipients as opposed to cellular bone marrow transplants may be preferable.

The SynerGraft valve: a new acellular (nonglutaraldehyde-fixed) tissue heart valve for autologous recellularization first experimental studies before clinical implantation.

The durability of current bioprosthetic heart valves is diminished by glutaraldehyde-associated leaflet calcification or by the associated absence of a cellular component capable of repair of wear-related damage. As a novel tissue engineering approach to improving replacement heart valve durability, we have developed a decellularization process to replace the use of cross-linking to limit xenograft antigenicity. The effectiveness of this process was assessed in a weanling sheep right ventricular outflow tract reconstruction model where valve function, calcification, and recellularization were examined. Porcine aortic valves were decellularized by a process designed to remove all histologically demonstrable leaflet cells. Stentless, bioprosthetic valves were fabricated from acellular tissues, cryopreserved, sterilized, and then implanted as pulmonary valve replacements in 4- to 6-month old female Suffolk sheep. Sheep aortic valves were implanted as allograft control subjects. After 150 days, the grafts were explanted and assessed histologically and by atomic absorption spectrophotometry for calcium content. All valves were hemodynamically functional at explant. Histological examination showed intact leaflets with in-growth of host fibroblastoid cells in all explanted porcine valves and no evidence of calcification. Porcine leaflet calcium content was unchanged over the duration of the implant (1.0+/-1.2 vs 1.5+/-1.8 mg/g dry weight, P = ns). Decellularization can stabilize xenogenic heart valves. Lack of calcification of acellular aortic leaflets suggests that prolonged durability of such valves is attainable without the use of cross-linking agents. The repopulation of the leaflet matrix offers additional promise of durability based on revitalization of the graft in vivo.

A rapid and sensitive cellular enzyme-linked immunoabsorbent assay (CELISA) for the detection and quantitation of antibodies against cell surface determinants. II. Optimal reagent concentrations and predictive analysis.

A cellular enzyme-linked immunosorbent assay (CELISA) was developed for the detection and quantification of antibodies elicited against allogeneic cell surface determinants. The technique uses a solid-phase cell matrix created by fixing cells with a mild formalin solution onto the bottom of a 96-well microtiter plate. A primary layer of alloantisera is first reacted against rat target cells. The secondary antibody, peroxidase conjugated antirat IgG, is then added to each well and serves as the second sandwich layer. Optimal reagent concentrations were determined by serial dilution analysis of various cell concentrations and secondary antibody dilutions. It was found that 200,000 cells per well was the optimal target cell concentration. However, 100,000 cells per well was also sufficient to run the assay with acceptable performance characteristics. Even lower cell concentrations of 10,000 and 20,000 cells/well, although not optimal, also produced acceptable results. Secondary antibody concentration with respect to the optimal cell concentration was determined to be 1:500. At 200,000 cells per well and a 1:500 secondary antibody dilution, the assay presented excellent coefficients of determination and high positive to negative ratios. The reaction was found to be very sensitive in yielding high antibody titers with low background levels and could be defined mathematically as a linear-log function. Titers of multiple unknown alloantibody samples were easily and accurately predicted in an automated manner by regression analysis form known standards. This immunoassay will be useful in studies of cell surface determinant expression and quantitation of antibodies reactive to such markers.

Graft-versus-host disease in limb transplantation: digital image analysis of bone marrow and TGF-beta expression in situ using a novel 3-D microscope.

A subpopulation of parental to hybrid VBMT recipients developed characteristic clinical and histopathologic manifestations of GVHD. These changes are similar to those seen in human GVHD secondary to bone marrow transplantation. Human GVHD also manifests itself in an acute and chronic manner. Only a minority (30% to 40%) of animals developed lethal GVHD in our model. Those animals developing GVHD had a significantly (P < .0001) higher expression of TGF-beta in situ compared to the tolerant subpopulation. The differential expression of TGF-beta may represent an important mechanism of immune dysregulation associated with GVHD in CTA recipients.

Use of regression analysis and flow cytometry for determining levels of mixed semiallogeneic immune chimerism.

It has been shown that tolerance or specific immunologic nonresponsiveness in various lymphohemopoietic transplant models can be associated with the development of mixed lymphoid chimerism. As a specific example, composite tissue (limb) allografts were studied as a model for vascularized bone marrow transplantation (VBMT) and it was demonstrated that development of stable cellular immune chimerism is associated with long-term allograft survival. Recently, studies were initiated using a new parental to hybrid VBMT model, but the detection of donor cells is complicated, due to the fact that they share one parental allotypic determinant. Therefore, regression analysis with a flow cytometric immunofluorescent staining assay was evaluated for the assessment of cellular lymphoid chimerism in donor parental to hybrid (P-->F1) lymphohemopoietic transplant models. Standard curves consisting of known mixed populations of parental donor (Lewis, LEW) and hybrid host F1 (Lew x BN, LBN) lymphocytes were established. Standard curves were analyzed by linear regression statistics and excellent coefficients of determination (r > .881) were obtained for all standard curves. A highly statistically significant (p < .016) linear relationship between level of donor cell chimerism (independent variable) and percent stained (dependent variable) was determined. The technique was then evaluated using the parental to hybrid VBMT model. Levels of donor LEW lymphoid chimerism in all VBMT LBN recipients were successfully assessed by regression analysis and inverse prediction using distinct recipient allodeterminant markers. In conclusion, this technique was proven to be reliable and accurate for the detection of of chimerism in parental to F1 lymphohemopoietic allograft models.

Chemotherapeutic treatment of malignant chordoma in children.

PURPOSE: We describe the effect of multiagent chemotherapy for malignant chordoma. Previous reports of other patients with malignant chordoma treated with chemotherapy as well as other therapeutic interventions are reviewed. PATIENTS AND METHODS: We describe a 19-month-old girl with unresectable cervical chordoma metastatic to the lungs at diagnosis treated with multiagent systemic chemotherapy. CNS disease was diagnosed after one course of therapy, and intrathecal chemotherapy was then administered. CONCLUSIONS: Ifosfamide and doxorubicin were efficacious in a patient with advanced metastatic disease, producing significant disease regression. The addition of intrathecal or intraventricular therapy with hydrocortisone, ARA-C, and methotrexate was effective in controlling CNS disease due to chordoma. There was no apparent benefit from the use of actinomycin-D, cyclophosphamide and vincristine nor the combination of cisplatin and 5-fluorouracil or high-dose methotrexate.

Overview of a 10-year experience on methods and compositions for inducing site-specific immunosuppression with topical immunosuppressants.

Methods and formulations have been successfully developed to bring about site-specific immune suppression of local T-cell-mediated immune responses involved in contact hypersensitivity, skin allograft rejection, and, putatively, autoimmune inflammatory conditions such as psoriasis. The induction of site-specific immune suppression results in reduced systemic pharmacology and toxicity. Certain formatulations have been devised that can effect dramatic transdermal drug delivery and systemic immunopharmacology. Local site-specific or systemic efficacy by transdermal delivery can be dependent upon carrier composition with respect to the hydrophilic/lipophilic nature of the solvent system, active principal solubilization, and concentration. Multiple classes of active immunosuppressive agents can be successfully combined to produce novel and extremely potent topical drugs. Specifically, either cyclosporine or rapamycin inhibit local inflammatory/immune responses by topical application to skin tissue in vivo. Rapamycin is particularly efficacious during the late local inflammatory/immune phase. Cyclosporine is particularly efficacious during the early local inflammatory-immune phase. Also, skin allograft survival may be prolonged via topical use of CyA, alone and in combination with other anti-inflammatory agents. This includes combined immunosuppressant and steroidal anti-inflammatory agents that can produce synergistic results. Systemic immunity in these instances is normal. Expression of MHC class I and MHC class II molecules is dramatically decreased in these CyA/steroid SITE-treated grafts. In summary, the induction of local immune suppression at the tissue site and focal responding immunocytes can result in surprising efficacy when used in conjunction with limited systemic administration, which could have significant immunologic and clinical ramifications.