Genetically engineered Sertoli cells are able to survive allogeneic transplantation

Complementing Testicular Immune Regulation: The Relationship between Sertoli Cells, Complement, and the Immune Response

Sertoli cells within the testis are instrumental in providing an environment for spermatogenesis and protecting the developing germ cells from detrimental immune responses which could affect fertility. Though these immune responses consist of many immune processes, this review focuses on the understudied complement system. Complement consists of 50+ proteins including regulatory proteins, immune receptors, and a cascade of proteolytic cleavages resulting in target cell destruction. In the testis, Sertoli cells protect the germ cells from autoimmune destruction by creating an immunoregulatory environment. Most studies on Sertoli cells and complement have been conducted in transplantation models, which are effective in studying immune regulation during robust rejection responses. In grafts, Sertoli cells survive activated complement, have decreased deposition of complement fragments, and express many complement inhibitors. Moreover, the grafts have delayed infiltration of immune cells and contain increased infiltration of immunosuppressive regulatory T cells as compared to rejecting grafts. Additionally, anti-sperm antibodies and lymphocyte infiltration have been detected in up to 50% and 30% of infertile testes, respectively. This review seeks to provide an updated overview of the complement system, describe its relationship with immune cells, and explain how Sertoli cells may regulate complement in immunoprotection. Identifying the mechanism Sertoli cells use to protect themselves and germ cells against complement and immune destruction is relevant for male reproduction, autoimmunity, and transplantation.

Immunoregulatory Sertoli Cell Allografts Engineered to Express Human Insulin Survive Humoral-Mediated Rejection

An effective treatment and possible cure for type 1 diabetes is transplantation of pancreatic islets. Unfortunately, transplanted islets are rejected by the immune system with humoral-mediated responses being an important part of rejection. Sertoli cells (SC), an immune regulatory cell shown to survive as allografts long-term without immunosuppressants, have the potential to be used as a cell-based gene therapy vehicle to deliver endogenous insulin-a possible alternative to islets. Previously, we transduced a mouse SC line to produce human insulin. After transplantation into diabetic mice, these cells consistently produced low levels of insulin with graft survival of 75% at 50 days post-transplantation. The object of this study was to assess humoral immune regulation by these engineered SC. Both nontransduced and transduced SC survived exposure to human serum with complement in vitro. Analysis of allografts in vivo at 20 and 50 days post-transplantation revealed that despite IgG antibody detection, complement factor deposition was low and grafts survived through 50 days post-transplantation. Furthermore, the transduced SC secreted elevated levels of the complement inhibitor C1q binding protein. Overall, this suggests SC genetically engineered to express insulin maintain their ability to prevent complement-mediated killing. Since inhibiting complement-mediated rejection is important for graft survival, further studies of how SC modifies the immune response could be utilized to advance the use of genetically engineered SC or to prolong islet allograft survival to improve the treatment of diabetes.

Mouse Sertoli cells isolation by lineage tracing and sorting

Sertoli cells play a key role in spermatogenesis by supporting the germ cells throughout differentiation. The isolation of Sertoli cells is essential to study their functions. However, the close contact of Sertoli cells with other testicular cell types and the high proliferation of contaminating cells are obstacles to obtain pure primary cultures. Current rodent Sertoli cell isolation protocols result in enriched, rather than pure Sertoli cells. Therefore, novel approaches are necessary to improve the purity of Sertoli cell primary cultures. The goal of this study is to obtain pure mouse Sertoli cells using lineage tracing and fluorescence-activated cell sorting (FACS). We bred the Amh-Cre mouse line with tdTomato line to generate mice constitutively expressing red fluorescence specifically in Sertoli cells. Primary cultures of Sertoli cells isolated from prepubertal mice showed that 79% of cells expressed tdTomato, as evaluated by fluorescence microscopy and flow cytometry; however, nearly all adherent cells were positive for vimentin. Most of the tomato-negative cells expressed α-smooth muscle actin (α-SMA), a peritubular myoid cell marker, but double-negative populations were also present. These findings suggest that vimentin lacks Sertoli cell-specificity and that α-SMA is not adequate to identify all of the contaminating cells. Upon FACS sorting; however, virtually 100% of the cells were tdTomato positive, expressed vimentin, but not α-SMA. Prepubertal mice yielded a higher number of Sertoli cells compared to adults, but both could be adequately sorted. In conclusion, our study shows that lineage tracing and sorting is an efficient strategy for acquiring pure populations of murine Sertoli cells.

Sertoli Cells Engineered to Express Insulin to Lower Blood Glucose in Diabetic Mice

Long-term survival of allo- and xenotransplanted immune-privileged Sertoli cells (SCs) is well documented suggesting that SCs can be used to deliver foreign proteins for cell-based gene therapy. The aim of this study was to use a lentivirus carrying proinsulin cDNA to achieve stable expression and lowering of blood glucose levels (BGLs). A SC line transduced with the lentivirus (MSC-LV-mI) maintained stable insulin expression in vitro. These MSC-LV-mI cells were transplanted and grafts were analyzed for cell survival, continued proinsulin mRNA, and insulin protein expression. All grafts contained MSC-LV-mI cells that expressed proinsulin mRNA and insulin protein. Transplantation of MSC-LV-mI cells into diabetic mice significantly lowered BGLs for 4 days after transplantation. Interestingly, in three transplanted SCID mice and one transplanted BALB/c mouse, the BGLs again significantly lowered by day 50 and 70, respectively. This is the first time SC transduced with a lentiviral vector was able to stably express insulin and lower BGLs. In conclusion, a SC line can be modified to stably express therapeutic proteins (e.g., insulin), thus taking us one step further in the use of SCs as an immune-privileged vehicle for cell-based gene therapy.

Sertoli Cells Induce Systemic Donor-Specific Tolerance in Xenogenic Transplantation Model

Cell therapy is a potentially powerful tool in the treatment of many grave disorders including leukemia, immune deficiencies, autoimmune diseases, and diabetes. However, finding matched donors is challenging and recipients may suffer from the severe complications of systemic immune suppression. Sertoli cells, when cotransplanted with both allo- and xenograft tissues, promote graft acceptance in the absence of systemic immunosuppression. How Sertoli cells do this is not, as yet, clearly defined. We have examined the ability of Sertoli cells to produce systemic immune tolerance. For this purpose, Sertoli cells were injected into an otherwise normal C57/BL6 mouse host via the lateral tail vein. No other immunosuppressive protocols were applied. Six to 8 weeks posttransplantation, blood was collected for analysis of cytokine levels. Tolerance to donor cells was determined by mixed lymphocytic culture, and production of T-cell-dependent antibody was determined by an in vitro anti-sheep red blood cell plaque-forming assay. Results showed a marked modulation of immune cytokines in the transplanted mouse host and donor-specific transplantation tolerance was achieved. Tolerant mouse lymphocytes maintained a competent humoral antibody response. Additionally, C57/BL6 mice transplanted with rat Sertoli cells tolerated rat skin grafts significantly longer than control non-Sertoli cell transplanted mice. We conclude that systemic administration of rat Sertoli cells across xenogenic barrier induces transplantation tolerance without altering systemic immune competence. These data suggest that Sertoli cells may be used as a novel and potentially powerful tool in cell transplantation therapy.

The Sertoli cell: one hundred fifty years of beauty and plasticity

It has been one and a half centuries since Enrico Sertoli published the seminal discovery of the testicular 'nurse cell', not only a key cell in the testis, but indeed one of the most amazing cells in the vertebrate body. In this review, we begin by examining the three phases of morphological research that have occurred in the study of Sertoli cells, because microscopic anatomy was essentially the only scientific discipline available for about the first 75 years after the discovery. Biochemistry and molecular biology then changed all of biological sciences, including our understanding of the functions of Sertoli cells. Immunology and stem cell biology were not even topics of science in 1865, but they have now become major issues in our appreciation of Sertoli cell's role in spermatogenesis. We end with the universal importance and plasticity of function by comparing Sertoli cells in fish, amphibians, and mammals. In these various classes of vertebrates, Sertoli cells have quite different modes of proliferation and epithelial maintenance, cystic vs. tubular formation, yet accomplish essentially the same function but in strikingly different ways.

Genetically engineered immune privileged Sertoli cells: A new road to cell based gene therapy

Sertoli cells are immune privileged cells, important for controlling the immune response to male germ cells as well as maintaining the tolerogenic environment in the testis. Additionally, ectopic Sertoli cells have been shown to survive and protect co-grafted cells when transplanted across immunological barriers. The survival of ectopic Sertoli cells has led to the idea that they could be used in cell based gene therapy. In this review, we provide a brief overview of testis immune privilege and Sertoli cell transplantation, factors contributing to Sertoli cell immune privilege, the challenges faced by viral vector gene therapy, the use of immune privileged cells in cell based gene therapy and describe several recent studies on the use of genetically engineered Sertoli cells to provide continuous delivery of therapeutic proteins.

Cell lines: Valuable tools or useless artifacts

Cell lines are often used in place of primary cells to study biological processes. However, care must be taken when interpreting the results as cell lines do not always accurately replicate the primary cells. In this article, we will briefly talk about advantages and disadvantages of cell lines and then discuss results using the mouse Sertoli cell line, MSC-1, compared with primary mouse Sertoli cells. MSC-1 cells resemble Sertoli cells morphologically and possess several biochemical markers associated with Sertoli cells. Studies have demonstrated that the function and regulation of retinoic acid receptor α (RARα) is similar between MSC-1 and rat Sertoli cells. However, MSC-1 cells lack some of the immune privilege properties associated with primary Sertoli cells, including survival in animals with a fully functional immune system. Therefore, it has to be kept in mind that cell lines do not behave identically with primary cells and should not be used to replace primary cells. In order to strengthen the findings, key control experiments using primary cells should always be performed.

Sustained expression of insulin by a genetically engineered sertoli cell line after allotransplantation in diabetic BALB/c mice

Immune-privileged Sertoli cells (SCs) exhibit long-term survival after allotransplantation or xenotransplantation, suggesting they can be used as a vehicle for cell-based gene therapy. Previously, we demonstrated that SCs engineered to secrete insulin by using an adenoviral vector normalized blood glucose levels in diabetic mice. However, the expression of insulin was transient, and the use of immunocompromised mice did not address the question of whether SCs can stably express insulin in immunocompetent animals. Thus, the objective of the current study was to use a lentiviral vector to achieve stable expression of insulin in SCs and test the ability of these cells to survive after allotransplantation. A mouse SC line transduced with a recombinant lentiviral vector containing furin-modified human proinsulin cDNA (MSC-EhI-Zs) maintained stable insulin expression in vitro. Allotransplantation of MSC-EhI-Zs cells into diabetic BALB/c mice demonstrated 88% and 75% graft survival rates at 20 and 50 days post-transplantation, respectively. Transplanted MSC-EhI-Zs cells continued to produce insulin mRNA throughout the study (i.e., 50 days); however, insulin protein was detected only in patches of cells within the grafts. Consistent with low insulin protein detection, there was no significant change in blood glucose levels in the transplant recipients. Nevertheless, MSC-EhI-Zs cells isolated from the grafts continued to express insulin protein in culture. Collectively, this demonstrates that MSC-EhI-Zs cells stably expressed insulin and survived allotransplantation without immunosuppression. This further strengthens the use of SCs as targets for cell-based gene therapy for the treatment of numerous chronic diseases, especially those that require basal protein expression.

Immunoprotective properties of primary Sertoli cells in mice: potential functional pathways that confer immune privilege

Primary Sertoli cells isolated from mouse testes survive when transplanted across immunological barriers and protect cotransplanted allogeneic and xenogeneic cells from rejection in rodent models. In contrast, the mouse Sertoli cell line (MSC-1) lacks immunoprotective properties associated with primary Sertoli cells. In this study, enriched primary Sertoli cells or MSC-1 cells were transplanted as allografts into the renal subcapsular area of naive BALB/c mice, and their survival in graft sites was compared. While Sertoli cells were detected within the grafts with 100% graft survival throughout the 20-day study, MSC-1 cells were rejected between 11 and 14 days, with 0% graft survival at 20 days posttransplantation. Nonetheless, the mechanism for primary Sertoli cell survival and immunoprotection remains unresolved. To identify immune factors or functional pathways potentially responsible for immune privilege, gene expression profiles of enriched primary Sertoli cells were compared with those of MSC-1 cells. Microarray analysis identified 2369 genes in enriched primary Sertoli cells that were differentially expressed at ±4-fold or higher levels than in MSC-1 cells. Ontological analyses identified multiple immune pathways, which were used to generate a list of 340 immune-related genes. Three functions were identified in primary Sertoli cells as potentially important for establishing immune privilege: suppression of inflammation by specific cytokines and prostanoid molecules, slowing of leukocyte migration by controlled cell junctions and actin polymerization, and inhibition of complement activation and membrane-associated cell lysis. These results increase our understanding of testicular immune privilege and, in the long-term, could lead to improvements in transplantation success.

Role of interleukin 17 in arthritis chronicity through survival of synoviocytes via regulation of synoviolin expression

BACKGROUND

The use of TNF inhibitors has been a major progress in the treatment of chronic inflammation. However, not all patients respond. In addition, response will be often lost when treatment is stopped. These clinical aspects indicate that other cytokines might be involved and we focus here on the role of IL-17. In addition, the chronic nature of joint inflammation may contribute to reduced response and enhanced chronicity. Therefore we studied the capacity of IL-17 to regulate synoviolin, an E3 ubiquitin ligase implicated in synovial hyperplasia in human rheumatoid arthritis (RA) FLS and in chronic reactivated streptococcal cell wall (SCW)-induced arthritis.

METHODOLOGY/PRINCIPAL FINDINGS

Chronic reactivated SCW-induced arthritis was examined in IL-17R deficient and wild-type mice. Synoviolin expression was analysed by real-time RT-PCR, Western Blot or immunostaining in RA FLS and tissue, and p53 assessed by Western Blot. Apoptosis was detected by annexin V/propidium iodide staining, SS DNA apoptosis ELISA kit or TUNEL staining and proliferation by PCNA staining. IL-17 receptor A (IL-17RA), IL-17 receptor C (IL-17-RC) or synoviolin inhibition were achieved by small interfering RNA (siRNA) or neutralizing antibodies. IL-17 induced sustained synoviolin expression in RA FLS. Sodium nitroprusside (SNP)-induced RA FLS apoptosis was associated with reduced synoviolin expression and was rescued by IL-17 treatment with a corresponding increase in synoviolin expression. IL-17RC or IL-17RA RNA interference increased SNP-induced apoptosis, and decreased IL-17-induced synoviolin. IL-17 rescued RA FLS from apoptosis induced by synoviolin knockdown. IL-17 and TNF had additive effects on synoviolin expression and protection against apoptosis induced by synoviolin knowndown. In IL-17R deficient mice, a decrease in arthritis severity was characterized by increased synovial apoptosis, reduced proliferation and a marked reduction in synoviolin expression. A distinct absence of synoviolin expressing germinal centres in IL-17R deficient mice contrasted with synoviolin positive B cells and Th17 cells in synovial germinal centre-like structures.

CONCLUSION/SIGNIFICANCE

IL-17 induction of synoviolin may contribute at least in part to RA chronicity by prolonging the survival of RA FLS and immune cells in germinal centre reactions. These results extend the role of IL-17 to synovial hyperplasia.

Delivery of a therapeutic protein by immune-privileged Sertoli cells

Immune-privileged Sertoli cells survive long term after allogeneic or xenogeneic transplantation without the use of immunosuppressive drugs, suggesting they could be used as a vehicle to deliver therapeutic proteins. As a model to test this, we engineered Sertoli cells to transiently produce basal levels of insulin and then examined their ability to lower blood glucose levels after transplantation into diabetic SCID mice. Mouse and porcine Sertoli cells transduced with a recombinant adenoviral vector containing furin-modified human proinsulin cDNA expressed insulin mRNA and secreted insulin protein. Transplantation of 5-20 million insulin-expressing porcine Sertoli cells into diabetic SCID mice significantly decreased blood glucose levels in a dose-dependent manner, with 20 million Sertoli cells decreasing blood glucose levels to 9.8 ± 2.7 mM. Similar results were obtained when 20 million insulin-positive, BALB/c mouse Sertoli cells were transplanted; blood glucose levels dropped to 6.3 ± 2.4 mM and remained significantly lower for 5 days. To our knowledge, this is the first study to demonstrate Sertoli cells can be engineered to produce and secrete a clinically relevant factor that has a therapeutic effect, thus supporting the concept of using immune-privileged Sertoli cells as a potential vehicle for gene therapy.

Immunoprotective Sertoli cells: making allogeneic and xenogeneic transplantation feasible

The testis as an immune-privileged site allows long-term survival of allogeneic and xenogeneic transplants. Testicular Sertoli cells (SCs) play a major role in this immunoprotection and have been used to create an ectopic immune-privileged environment that prolongs survival of co-transplanted allogeneic and xenogeneic cells, including pancreatic islets and neurons. Extended survival of such grafts testifies to the immunoprotective properties of SCs. However, there is still variability in the survival rates of the co-grafted cells and rarely are 100% of the grafts protected. This emphasizes the need to learn more about what is involved in creating the optimal immunoprotective milieu. Several parameters including organization of the SCs into tubule-like structures and the production of immunomodulatory factors by SCs, specifically complement inhibitors, cytokines, and cytotoxic lymphocyte inhibitors, are likely important. In addition, an intricate interplay between several of these factors may be responsible for providing the most ideal environment for protection of the co-transplants by SCs. In this review, we will also briefly describe a novel use for the immune-privileged abilities of SCs; engineering them to deliver therapeutic proteins for the treatment of diseases like diabetes and Parkinson's disease. In conclusion, further studies and more detailed analysis of the mechanisms involved in creating the immune-protective environment by SCs may make their application in co-transplantation and as engineered cells clinically feasible.

Sertoli cell line lacks the immunoprotective properties associated with primary Sertoli cells

Sertoli cells are important for maintenance of the immune privileged environment of the testis and prolong survival of cotransplanted cells. The objective of the current study was to examine the immunoprotective properties of a mouse Sertoli cell line (MSC-1) in order to identify a Sertoli cell line that could be used to aid in investigation of the immunoprotective abilities of Sertoli cells. BALB/c islets were cotransplanted with 0-9 million primary BALB/c Sertoli cells or MSC-1 cells into diabetic C3H or BALB/c mice and protection of grafted islets was examined by monitoring blood glucose levels and immunohistochemical analysis. Additionally, expression of potential immunoprotective factors in MSC-1 cells was examined. Cotransplantation of islets with 3 million primary Sertoli cells significantly prolonged islet allograft survival (61.1 +/- 6.9 days; p < 0.05) compared with control mice that received allogeneic islets alone (26.9 +/- 2.1 days). Grafts collected from normoglycemic C3H mice at 100 days posttransplant contained insulin-positive beta-cells adjacent to allogeneic Sertoli cells arranged in tubule-like structures. In contrast, cotransplantation of islet allografts with MSC-1 cells did not prolong islet survival (average 29.8 +/- 3.3 days) regardless of the number of MSC-1 cells transplanted and the rejected grafts contained very few beta-cells and randomly arranged MSC-1 cells. The lack of islet cell survival was not due to detrimental effects of MSC-1 cells because syngneic islets cotransplanted with MSC-1 cells were functional throughout the study. MSC-1 cells were found to express known Sertoli cell-expressed, immunoprotective factors, clusterin, Fas ligand, and transforming growth factor-beta1, suggesting additional factors may be involved in Sertoli cell immune privilege. These data indicate the MSC-1 cell line lacks the immunoprotective properties associated with primary Sertoli cells. Further study of this cell line could be useful in examining the mechanisms that enable Sertoli cells to provide immune privilege.

Shifting the balance: cell-based therapeutics as modifiers of the amyotrophic lateral sclerosis–specific neuronal microenvironment

✓ Recent advances in the laboratory have improved the current understanding of neurobiological mechanisms underlying the initiating events and pathological progression observed in amyotrophic lateral sclerosis (ALS). Whereas initial studies have revealed the late-stage intracellular cascades contributing to neuronal dysfunction and cell death, more recently collected data have begun to elucidate the presence and importance of a “non–cell autonomous” component indicating that affected glial cell subtypes may serve distinct and required roles. Pharmacological interventions for ALS have largely been disappointing likely in part because they have failed to address either the proximate events contributing to neuronal dysfunction and death or the deleterious contributions of non-neuronal cells within the local microenvironment. Alternatively, cell-based therapeutics offer the potential of a multifaceted approach oriented toward the dual ends of protecting remaining viable neurons and attempting to restore neuronal function lost as a manifestation of disease progression. The authors review the evolving knowledge of disease initiation and progression, with specific emphasis on the role of affected glia as crucial contributors to the observed ALS phenotype. This basis is used to underscore the potential roles of cell-based therapeutics as modifiers of the ALS-specific microenvironment.

Identification of a Novel Human Granzyme B Inhibitor Secreted by Cultured Sertoli Cells

Sertoli cells have long since been recognized for their ability to suppress the immune system and protect themselves as well as other cell types from harmful immune reaction. However, the exact mechanism or product produced by Sertoli cells that affords this immunoprotection has never been fully elucidated. We examined the effect of mouse Sertoli cell-conditioned medium on human granzyme B-mediated killing and found that there was an inhibitory effect. We subsequently found that a factor secreted by Sertoli cells inhibited killing through the inhibition of granzyme B enzymatic activity. SDS-PAGE analysis revealed that this factor formed an SDS-insoluble complex with granzyme B. Immunoprecipitation and mass spectroscopic analysis of the complex identified a proteinase inhibitor, serpina3n, as a novel inhibitor of human granzyme B. We cloned serpina3n cDNA, expressed it in Jurkat cells, and confirmed its inhibitory action on granzyme B activity. Our studies have led to the discovery of a new inhibitor of granzyme B and have uncovered a new mechanism used by Sertoli cells for immunoprotection.

Nerve growth factor in treatment and pathogenesis of Alzheimer's disease

The etiology of Alzheimer's disease (AD) is still unknown. In addition, this terrible neurodegenerative disease will increase exponentially over the next two decades due to longer lifespan and an aging "baby-boomer" generation. All treatments currently approved for AD have moderate efficacy in slowing the rate of cognitive decline in patients, and no efficacy in halting progression of the disease. Hence, there is an urgent need for new drug targets and delivery methods to slow or reverse the progression of AD. One molecule that has received much attention in its potential therapeutic role in AD is nerve growth factor (NGF). This review will demonstrate data from humans and animals which promote NGF as a potential therapeutic target by (1) outlining the hypothesis behind using NGF for the treatment of AD, (2) reviewing both the normal and AD altered signaling pathways and effects of NGF in the central nervous system (CNS), and (3) examining the results of NGF treatment obtained from animal models of AD and AD patients.

Suitability of allogeneic sertoli cells for ex vivo gene delivery in the injured spinal cord

Cell-based gene delivery for gene therapy offers the advantages of long-term stable expression of proteins without the safety concerns associated with viral vectors. However, issues of immune rejection prevent the widespread use of allogeneic cell implants. In this study, we determine if Sertoli cells, known for their immune privileged status, are suitable vehicles for allogeneic cell-based gene delivery into the injured spinal cord. As proof of concept, Sertoli cells were modified with recombinant adenovirus expressing enhanced green fluorescent protein (eGFP) or a human trophic factor, neurotrophin-3 (hNT-3), and eGFP. Genetically modified Sertoli cells retained their immunosuppressive ability in vitro, based upon lymphocyte proliferation assays, and were capable of generating biologically relevant levels of NT-3. Similarly, modified, allogeneic cells, implanted into the acutely injured spinal cord, reduced the early inflammatory response while producing significant levels of hNT-3 for at least 3 days after grafting. Moreover, these cells survived for at least 42 days after implantation in the injured cord. Together, these results demonstrate that Sertoli cells function in immunomodulation, can be engineered to produce bioactive molecules, and show long-term survival after implantation into the hostile environment of the acutely injured spinal cord. Such long-term survival represents an important first step toward developing an optimal cell-based delivery system that generates sustained expression of a therapeutic molecule.

Enhancement of adenovirus-mediated gene delivery to rheumatoid arthritis synoviocytes and synovium by fiber modifications: role of arginine-glycine-aspartic acid (RGD)- and non-RGD-binding integrins

Rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) do not express the coxsackie-adenovirus (Ad) receptor and are poorly permissive to Ad serotype 5 (Ad5). Genetically modified, coxsackie-Ad receptor-independent Ad5 vectors were studied for gene delivery in human RA FLS and synovium explants and murine collagen-induced arthritis. Short-fiber Ad5 vectors with seven fiber shaft repeats Ad5GFP-R7-knob, Ad5GFP-R7-arginine-glycine-aspartic acid (RGD) (RGD-liganded), and Ad5GFPDeltaknob (knob-deleted) were compared with Ad5GFP-FiWT, a conventional wild-type (WT) Ad5 vector. Gene transfer by Ad5GFP-R7-knob and Ad5GFP-R7-RGD was 40- to 50-fold and 25-fold higher, respectively, than Ad5GFP-FiWT in FLS. Ad5GFPDeltaknob was more efficacious than its knob-bearing version Ad5GFP-R7-knob in FLS transduction. Virus attachment and entry required RGD- and LDV-binding integrins including alpha(v), alpha(v)beta3, a(v)beta5, and beta1. Ad5GFP-R7-knob infection of FLS was partially neutralized by synovial fluid (SF), but remained 30- to 40-fold higher than Ad5GFP-FiWT in the presence of SF. Ad5GFPDeltaknob was partially neutralized by SF at low virus input, but escaped viral neutralization by SF at higher virus input. Gene transfer to human synovium ex vivo explants and murine collagen-induced arthritis in vivo was also more efficient with short fiber-modified vectors (with and without the knob domain) than Ad5GFPFiWT. Gene transfer by short fiber-modified vectors was enhanced by inflammatory cytokines in vitro and in the presence of inflammation in murine synovium in vivo. Our data indicated that the highly efficient gene delivery RA was mediated by RGD- and non-RGD-binding integrins and enhanced by inflammation. Short fiber modifications with knob ablation may be a strategy to enhance gene delivery, reducing vector dose and vector-induced inflammation and toxicity.

Sertoli cells improve survival of motor neurons in SOD1 transgenic mice, a model of amyotrophic lateral sclerosis

Cell replacement therapy has been widely suggested as a treatment for multiple diseases including motor neuron disease. A variety of donor cells have been tested for treatment including isolated preparations from bone marrow and embryonic spinal cord. Another cell source, Sertoli cells, have been successfully used in models of diabetes, Parkinson's disease and Huntington's disease. The ability of these cells to secrete cytoprotective proteins and their role as 'nurse cells' supporting the function of other cell types in the testes suggest their potential use as neuroprotective cells. The current study examines the ability of Sertoli cells injected into the parenchyma of the spinal cord to protect motor neurons in a mouse model for amyotrophic lateral sclerosis. Seventy transgenic mice expressing the mutant (G93A) human Cu-Zn superoxide dismutase (SOD1) received a unilateral spinal injection of Sertoli-enriched testicular cells into the L4-L5 ventral horn (1 x 10(5) cells total) prior to the onset of clinical symptoms. The animals were euthanized at the end stage of the disease. Histological and morphometric analyses of the transplant site were performed. A significant increase in the number of surviving ChAT positive motor neurons was found ipsilateral to the injection compared with contralateral and uninjected spinal cord. The ipsilateral increase in motor neuron density was dependent upon proximity to the injection site. Sections rostral or caudal to the injection site did not display a similar difference in motor neuron density. Implantation of a Sertoli-cell-enriched preparation has a significant neuroprotective benefit to vulnerable motor neurons in the SOD1 transgenic model. The therapeutic benefit may be the result of secreted neurotrophic factors present at a critical stage of motor neuron degeneration in this model.

Solid tissues can be manipulated ex vivo and used as vehicles for gene therapy

BACKGROUND

Organ fragments can be cultured for weeks in vitro if they are prepared of microscopic thickness and if the basic organ structure is preserved. Such organ fragments, which we termed micro-organs (MOs), express in culture endogenous tissue-specific gene products. We have exploited this methodology to engineer MOs ex vivo by gene transfer.

METHODS

MOs prepared from spleen, lung, colon and skin were infected using: herpes simplex type-1, adeno virus, vaccinia virus and murine leukemia virus (MuLV), carrying the reporter gene beta-galactosidase.

RESULTS

All four viral vectors infected MOs in culture, with adeno infection giving significantly higher values. After optimization, high levels of expression (> 15% positive cells), comparable to those obtained with the adeno construct, were also obtained using the MuLV construct both in vitro and after implantation into syngeneic hosts. After implantation, the engineered tissue was found to remain localized, become vascularized, and to express the transduced gene for several months.

CONCLUSIONS

The system can be used to study interactions between viruses and tissues both ex vivo and in vivo. Furthermore, the approach proposes a novel platform for ex vivo gene therapy. Such engineered structures could be used as autologous biological pumps for continuous secretion in vivo of gene products of clinical importance.

Use of Sertoli cell transplants to provide local immunoprotection for tissue grafts

The recent success of allogeneic islet transplantation for the treatment of type I diabetes has renewed interest in cell therapy for diseases of secretory cell dysfunction. Unfortunately, widespread clinical use of cell transplantation is limited by tissue availability and the need for long-term immunosuppresion. Testicular Sertoli cells can confer local immunoprotection for co-transplanted cells and may provide a means of overcoming the obstacles associated with cell transplantation. Sertoli cell grafts protect islets in animal models of diabetes and can be transplanted into the brain to enhance regeneration and promote the survival of co-grafted tissues. This review describes the role that Sertoli cells normally play in testicular immunology, details the preclinical data using transplanted Sertoli cells in models of diabetes and Parkinson's disease and discusses some of the possible mechanisms involved in this phenomena, as well as the future of this technology.