Perspectives and controversies in the field of stem cell research

The fourth annual meeting of the International Society for Stem Cell Research focused on a number of pressing issues, including: (I) the need to better characterize the biology of stem cells; (II) the need to exploit and optimize the great therapeutic potential of stem cells in tissue regeneration; (III) ethical and safety considerations related to the use of human embryonic stem cells; (IV) the contribution of adult stem cells to carcinogenesis; (V) the need to investigate the biology of cancer stem cells. The purpose of this report is to summarize the current status of stem cell research, as surmised by the proceedings of this meeting.

Advances and perspectives in the field of gene transfer technology

The American Society of Gene Therapy 9th annual meeting, held May 31 to June 4, 2006, in Baltimore (Maryland, U.S.A.), focused on several aspects of gene transfer technology, such as vector development of a wide variety of gene delivery systems, stem cell research, gene expression, engineering of cell and animal models for the study of several pathological conditions, genetic immunization procedures, immunogenicity of vectors and transgenes, insertional mutagenesis and last, but not least, clinical and preclinical studies. Some advances were reported in the field of gene transfer technology; however, safety issues, such as insertional mutagenesis, and improvement of vector design remain at the top of the agenda of gene therapists.

Tyrosine hydroxylase gene regulation in human neuronal progenitor cells does not depend on Nurr1 as in the murine and rat systems

A previous study on the human tyrosine hydroxylase (TH) promoter revealed remarkable differences in the mechanism of TH gene regulation between the human and murine models. Indeed, a low degree of homology was observed in the sequence of TH promoters among human, mouse, and rat systems. Only five short conserved regions (CRs) could be identified among the three species. A human TH minimal promoter was engineered and assembled into a self-inactivating lentiviral vector system. This human TH minimal promoter contained the five CRs plus the first -194 bp from the transcription start of the human TH promoter and the first 35 bp of the untranslated messenger RNA leader of the human TH gene. A significant degree of specificity for this human TH minimal promoter was observed only for human neuronal progenitor cells (hNPCs), but not for TH-positive differentiated mouse primary striatal and substantia nigra cells, indicating a significant difference in TH gene regulation between the human and mouse systems. Not only is the degree of homology between the human and mouse promoters in the range of only 46%, but also those few elements that share a high degree of homology display totally different functions in human and mouse brain-derived cells. In the rodent system, NR4A2 (Nurr1) is required for the transactivation of TH minimal promoters. Intriguingly, neither the dimeric nor the heterodimeric binding sites for Nurr1 are present in the 13 kb DNA sequence that contains the human TH promoter. Instead, the CRs termed one and four of the human TH promoter encode only for a half palindromic binding site sequence for Nurr1, which failed to bind Nurr1 in an in vitro electrophoretic mobility shift assay (EMSA). Additionally, of the three monomeric NGFI-B response element (NBRE) core sites (AGGTCA) and two NBRE-related sites present in the human TH promoter, only one core and two NBRE-related sites formed protein binding complexes. Interestingly, there was no increase of protein binding complex formation upon TH induction and in no case could antibodies supershift Nurr1 from the complex. These findings, taken together, demonstrate that NBRE-related binding sites for Nurr1 do not play a direct role in mediating an interaction between Nurr1 and the human TH promoter. Likewise, immunohistochemical and Western blot analysis have also confirmed that both endogenous and exogenous Nurr1 expression does not positively correlate with TH gene expression in hNPCs, in contrast to the mouse model. In addition, real-time PCR analysis revealed that the downregulation of human Nurr1 gene expression mediated by silencing RNA molecules did not affect human TH gene expression in differentiated hNPCs. A better understanding of human TH gene regulation may have important implications both for the development of novel therapeutic approaches and the study of the pathogenesis of a variety of neurological illnesses, including Parkinson's disease, bipolar disorder, and schizophrenia.

[Laparoscopic treatment of adrenal myelolipoma: case report and review of the literature]

Adrenal myelolipoma is a rare benign, non-functioning tumor consisting of fat and hematopoietic tissues. In January 2005 we had observed an adrenal myelolipoma in 70 year old man. During the follow-up for bladder urothelioma, an abdominal CT revaled a well delineated 4x4 cm homogeneous fatty mass in the right suprarenal area with negative attenuation values. The functional study of adrenal gland was normal. The patient underwent videolaparoscopic right adrenalectomy (Gagner technique). Postoperative course was uneventful. The istological diagnosis showed adrenal myelolipoma. We conclude that videolaparoscopic adrenalectomy should be considered the gold standard treatment for benign adrenal lesions.

Immunity to poliovirus among children and the elderly in north-east Italy

INTRODUCTION

Italy and Europe were declared polio-free in June 2002, but increasing migration, even from undeveloped countries where polio still exists, may lead to a come-back of circulating poliovirus (PV) and infection in previously polio-free areas. It is consequently advisable to continue to monitor the immunity of the population in polio-free areas. The aim of this study was to assess the current prevalence of neutralizing antibodies in recently-immunized children and in elderly people who were never vaccinated.

METHODS

Sera from 511 healthy subjects resident in the Veneto Region were examined to assay their antibody titer for PV 1, 2 and 3, using the microneutralization test. Data were analyzed by chi-squared test, Student's t-test and linear regression analysis, using EPI-Info 2000 supplied by the Centers for Disease Control and Prevention (Atlanta, GA, USA).

RESULTS

Neutralizing antibodies in group A (231 subjects aged 1-17 years) showed significantly higher geometric mean titers (GMTs) than in group B (280 subjects aged 65-100 years) for all three PV serotypes (P < 0.001). Nobody simultaneously lacked neutralizing antibodies for all three serotypes. There were no difference between the two groups in terms of male/female GMTs for the three PV Antibodies decreased with time since vaccination, but the difference was only significant for PV 3. GMTs were lower in the elderly, with no significant difference among the three PV.

DISCUSSION

The population examined showed a good level of protection against the three PV strains: both groups A (vaccinated) and B (naturally immunized) revealed a valid immunity to poliovirus.

CONCLUSION

Immunization programs and immunity status population screening are still advisable until polio has been world-wide eradicated.

Somatostatin receptor subtypes mediate contractility on human colonic smooth muscle cells

This study demonstrates the expression of functional somatostatin receptor (sstr) subtypes in human circular and longitudinal colonic smooth muscle cells (SMC). Native somatostatin (SS) and sstr subtype-specific analogues were used to characterize the sstr subtypes present in both cell types by contraction/relaxation studies. Qualitative and quantitative mRNA analysis and immunohistochemistry of sstr subtypes were also carried out. sstr subtype 2 mRNA was expressed in circular SMC, and various levels of subtypes 1, 2 and 3 mRNA were expressed in longitudinal colonic SMC. Native SS and each subtype-specific analogue exerted a modest, but significant, contraction, although inhibition of carbachol-induced contraction (relaxation) was the main effect on SMC from both layers. CH-288, a sstr subtype 1-specific analogue, and octreotide, a sstr subtype 2-specific analogue, were the most effective relaxant analogues on longitudinal and circular SMC, respectively. sstr subtypes display a distinct expression pattern on human colonic SMC; on circular SMC, subtype 2 is the only sstr, whereas sstr subtypes 1, 2 and 3 are expressed on human SMC isolated from the longitudinal layer. The contractile effects of SS are mediated through sstr subtype 2 and sstr subtype 1 on circular and longitudinal human colonic SMC, respectively.

Rituximab treatment for glomerulonephritis in HCV-associated mixed cryoglobulinaemia: efficacy and safety in the absence of steroids

OBJECTIVE

Rituximab, an anti-CD20 monoclonal antibody, has been used in lupus nephritis and membranous idiopathic nephropathy and has proved effective in non-renal manifestations of type II mixed cryoglobulinaemia (MC) syndrome. We investigated the possible efficacy and safety of rituximab in the treatment of cryoglobulinaemic nephritis.

METHODS

Five patients with active, biopsy-proven, glomerulonephritis in hepatitis C virus (HCV)-related type II MC syndrome were treated with four weekly infusions of rituximab (375 mg/m2) in monotherapy, without steroids whenever possible. Rituximab was the first-line therapy in three cases.

RESULTS

A rapid and sustained renal response was observed in all patients, in one of them without retreatment up to the last follow-up (month 21+). Renal biopsy was repeated after 6 months in one patient and histopathological improvement was documented. Three patients relapsed, at months +5, +7 and +12 of follow-up, respectively. Two of them were then retreated with rituximab and again presented a rapid improvement in renal function. Maintenance therapy with rituximab was performed in two patients: nephritis remission was maintained in both. Fc-gamma receptor 3a (FcgammaRIIIa) genotype characterization was consistent with the clinical response observed. Rituximab also proved effective against other active MC manifestations, when present. No major side-effects occurred and steroids were not required in the follow-up.

CONCLUSIONS

Rituximab may provide effective and safe therapy in type II MC-related glomerulonephritis, possibly as first-line therapy, avoiding steroids and hazardous immunosuppressive treatment.

The controversial role of adenoviral-derived vectors in gene therapy programs: Where do we stand?

The high immunogenicity of recombinant adenoviral vectors is one of the major issues in the field of gene therapy. Adenoviral-based vectors are susceptible both to cytotoxic T-lymphocyte and humoral immune responses. In addition, leaky adenoviral genes also render transduced cells susceptible to host immune responses. These are the main reasons why adenoviral-based vectors are not suitable to correct genetic disorders, which require long-term expression of the transgene. Another limit to long-term transgene expression is posed by the fact that adenoviral-based vectors do not integrate their genome into the cellular chromosomal DNA of transduced cell populations. As it stands, adenoviral-mediated gene transfer is a promising tool for cancer therapy and for genetic immunization programs against infectious diseases, provided that host immune responses are carefully controlled.

Characterization of five evolutionary conserved regions of the human tyrosine hydroxylase (TH) promoter: implications for the engineering of a human TH minimal promoter assembled in a self-inactivating lentiviral vector system

A DNA fragment of about 13 kb containing the human tyrosine hydroxylase (TH) promoter was previously isolated from a genomic DNA library and sequenced. The 11 kb from the transcription start of the human TH promoter was successively joined to the green fluorescent protein (GFP) to generate a transgenic mouse model. High levels of GFP expression could be observed in TH-positive cells of the Substantia nigra of embryonic and adult mice. Intriguingly, the sequence of the human TH promoter showed a low degree of homology with the mouse and rat TH promoters. In fact, comparative analysis of the sequences of human, rat, and mouse TH promoters revealed only five small regions of high homology. These five evolutionarily conserved regions were numbered in numeric progression from the 5' end of human TH promoter. In the present study, a panel of minimal human TH promoters was generated to analyze the transcriptional activity and specificity of gene expression conferred by the five conserved regions (CRs). The series of constructs was termed 250 bp and contained the first -194 bp of the human TH promoter immediately upstream of the transcription start, the first 35 bp the human TH messenger RNA leader, plus one or more of the five CRs. All the constructs were assembled in a self-inactivating form of the latest series of lentiviral vector system based on the human immunodeficiency virus type 1 (HIV-1). Lentiviral-mediated gene transfer was highly efficient for the in vitro transduction of human neuronal progenitor cells (hNPCs). Since a subset of hNPCs express TH following in vitro treatment with a mixture of differentiating agents, it was possible to assess specificity of expression for all the minimal human TH promoters. Overall, the successive addition of the five conserved regions produced a greater degree of specificity in induced TH-positive hNPCs, in particular after the addition of CRI (-8,917, -8,876). However, the human TH minimal promoters did not show any specificity for TH-positive differentiated mouse primary striatal and S. nigra cells, indicating a difference of TH gene regulation between the human and mouse systems. The human TH minimal promoters may provide the opportunity for the selection of TH-positive human embryonic and adult stem cells for brain transplantation experiments in animal models for Parkinson's disease.

A 2-month cisplatin–epirubicin–paclitaxel (PET) weekly combination as primary systemic therapy for large operable breast cancer: a phase II study

PURPOSE

The present study aimed to define the antitumor activity of eight cisplatin-epirubicin-paclitaxel (PET) weekly cycles with granulocyte colony-stimulating factor (G-CSF) support in patients with large operable breast cancer.

METHODS

Operable breast cancer (T2-3 N0-1; T >3 cm) patients received eight preoperative weekly cycles of cisplatin 30 mg/m2, epirubicin 50 mg/m2 and paclitaxel 120 mg/m2, with G-CSF (5 microg/kg, days 3-5) support.

RESULTS

Sixty-three patients (T2/T3=30/33; N0/N+=8/55) were enrolled. Thirty-one clinical complete (49%) and 30 partial (48%) responses were recorded, giving a 97% response rate (95% confidence interval 89% to 100%). Breast-sparing surgery was performed in 32/63 (51%) patients. At pathological assessment, 28 patients (45%) showed absence of invasive residual disease in breast and 34 (55%) had negative axilla. In 20 women (32%) both breast and axilla were found to be disease-free. At a 23-month median follow-up (range 4-63), only eight relapses and two deaths had occurred, with the 4-year projected relapse-free and overall survival being 59% and 95%, respectively. Grade 3-4 neutropenia and anemia occurred in 24% and 5% of patients, respectively. Emesis, diarrhea and mucositis were the main non-hematological toxicities; however, only nine (14%) patients experienced one or more episodes of severe non-hematological toxicity. Peripheral neuropathy was frequent, but never severe.

CONCLUSIONS

A 2-month weekly treatment with PET represents a well tolerated and highly effective approach in large operable breast cancer patients. In spite of the short duration of chemotherapy, one-third of patients achieved a complete eradication of the tumor in both breast and axilla.

Role of Immunosuppressive Regimen on the Incidence and Characteristics of Cytomegalovirus Infection in Heart Transplantation: A Single-Center Experience With Preemptive Therapy

OBJECTIVE

This retrospective single-center report sought to evaluate the relation of immunosuppressive regimen with the incidence and characteristics of cytomegalovirus (CMV) infection from 1999 to 2003.

PATIENTS AND METHODS

Immunosuppression consisted of cyclosporine microemulsion (Neoral), azathioprine (AZA), and prednisolone associated with either thymoglobulin or ATG high-dosage induction from 1999 to 2000 (AZA, 64 patients [AZA-Thymo = 38 patients and AZA-ATG 26 patients]), or cyclosporine microemulsion (Neoral), mycophenolate mofetil (MMF), and prednisolone with low-dose thymoglobulin induction from 2001 onward (n = 52 patients). Ganciclovir preemptive therapy was guided by pp65 antigenemia monitoring without CMV prophylaxis.

RESULTS

The study groups were homogeneous with respect to major perioperative risk factors. Comparing the two AZA subgroups no difference emerged as to percentage of pp65 antigenemia-positive, preemptively treated patients reflecting CMV disease incidence and relapses. AZA-Thymo patient showed significantly shorter time to first positive pp65-antigenemia and higher viral load (AZA-Thymo vs AZA-ATG, P = .004 and P = .009). The two subgroups did not differ with regard to incidence of rejection, superinfection, and graft coronary disease. By shifting from AZA to MMF no difference emerged as to incidence and characteristics of CMV infections, but there was a significant reduction in acute rejection and superinfection (AZA vs MMF P = .001 and P = .008).

CONCLUSIONS

The distinct immunological properties of thymoglobulin versus ATG significantly altered the pattern of CMV expression. MMF with reduced-dose induction did not engender a higher CMV morbidity.

Anorectal atresia treated with non-continent pull through and artificial bowel sphincter: a case report

Anorectal atresia, which is classified as a low anorectal malformation, is characterised by the absence of the anal verge and by variable rectal atresia. In some cases, which have been classified as rectal agenesis, the atresia is associated with the absence of the internal sphincter. The therapeutic options are definitely surgical, aiming to relieve the bowel occlusion and to restore faecal continence by lowering the cul-de-sac to the perineum. We present the case of an adult patient with congenital rectal agenesis, double fistula (cul-de-sac-urethra and cul-de-sac-perineum) and caecostomy since birth. The patient was treated with a resection of sigmoid-rectum for the presence of a 20-cm faecaloma in the cul-de-sac, with a non-continent pull-through, and with implantation of an artificial bowel sphincter. Despite some difficulties in managing the device and a slight symptomatic mucosal prolapse, the results after 30 months have so far satisfied both the patient and the medical staff, especially in consideration of the limited number of alternative therapies.

pRb2/p130 decreases sensitivity to apoptosis induced by camptothecin and doxorubicin but not by taxol

PURPOSE

In addition to their original function as cell cycle regulators, retinoblastoma (Rb) family members were recently reported to modulate the sensitivity of cancer cells to chemotherapeutic agents. The purpose of this study is to investigate the possible role of pRb2/p130 in the sensitivity of ovarian cancer to camptothecin, doxorubicin, and taxol.

EXPERIMENTAL DESIGN

pRb2/p130 was overexpressed in the CAOV-3 ovarian cancer cell line, and the effect of pRb2/p130 overexpression on sensitivity to apoptosis trigged by IC(50) doses of different drugs was evaluated by various methods, including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and Western blot analyses.

RESULTS

The results reported in this study support the conclusion that overexpression of pRb2/p130 in the CAOV-3 ovarian cancer cell line lacking wild-type p53 is able to inhibit apoptosis triggered by camptothecin and doxorubicin through the c-Jun NH(2)-terminal kinase signaling transduction pathway. Conversely, taxol-induced cell death is not influenced by the pRb2/p130 protein level.

CONCLUSIONS

A careful analysis of pRb2/p130 expression in tumor specimens could help to identify the best clinical protocol to be used for each patient, improving efficacy and tolerance and therefore offering additional progress in the treatment of advanced ovarian cancer.

Altered laboratory thyroid parameters indicating hyperthyroidism in elderly subjects

The most common laboratory alterations of thyroid function indicating hyperthyroidism were evaluated in a series of 3015 subjects over 65 years of age by determining total T3, total T4 and TSH. Ultrasound and scintigraphy of the thyroid were performed where necessary. Our results showed a high prevalence of laboratory alterations hyperthyroidism type of around 8.09%, whereas the real prevalence (both clinical and laboratory) is 2.00% with a female/male ratio of 2.00. The most frequent hyperfunctioning thyreopaty is thyroidal adenoma (50%), followed by toxic multinodular goiter (33%) and Basedow's disease (17%). The most common clinical signs of hyperthyroidism involve the neuromuscular system and are often present in the so called 'euthyroid' elderly subject. We conclude that it is very difficult to diagnose hyperthyroidism in the elderly on clinical and laboratory grounds. The most significative laboratory thyroid parameter indicating hyperthyroidism seems to be TSH values below 0.2 IU/ml determined using the ultrasensitive IRMA method.

Exploring molecular motors and switches at the single-molecule level

Single-molecule techniques have propelled an impressive number of biophysical studies during the last decade. From relatively simple video-microscopy techniques, to sophisticated manipulation and detection apparata, single-molecule techniques are capable of tracking the movements and the reaction trajectories of single enzymatic units. By observing microspheres attached to biomolecules it is possible to follow the motion of molecular motors, or to detect conformational "switching" induced by regulatory proteins. Micromanipulation tools like optical tweezers have been widely applied to understand the mechanisms of linear molecular motors, and have allowed the measurement of the elementary steps and the forces produced by several motor proteins, including myosin, kinesin, and dynein. New experimental assays based on magnetic or optical "wrenches," which are able to apply and detect torques on rotary motors and biopolymers, are opening new possibilities in this field. Here, established and emerging magneto-optical manipulation and video-tracking techniques are reviewed, in the perspective of single molecular motors and regulatory proteins studies.

Current development of adeno-associated viral vectors

Vectors based on adeno-associated virus (AAV) have recently been used in phase I clinical trials for the treatment of neurological disorders, such as Parkinson's and Canavan's diseases. Indeed, AAV-mediated gene transfer is a promising tool for the delivery of therapeutic gene into the central and peripheral nervous systems. AAV-mediated gene transfer was also applied in phase I and phase II clinical trials for the treatment of cystic fibrosis and in phase I clinical trials for the treatment of hemophilia B. Remarkable progress is being reported in the development of AAV-based vectors; however, the design of AAV-derived vectors needs to be improved. As it stands, AAV-mediated gene transfer has a limited capacity in accommodating foreign genes. In addition, some preclinical studies have shown that AAV-derived vectors can cause tumors in animals due to insertional mutagenesis events. This review will discuss perspectives and drawbacks for AAV-based vector systems.

The role of adult stem cells in carcinogenesis

The role of adult stem cells in tissue regeneration has attracted much interest because of its enormous therapeutic potential. Adult stem cells reside in every tissue of the body and have the ability to self-renew and to give rise to a high number of differentiated progeny. These are indeed the essential steps in tissue regeneration, which in some cases occurs constitutively, whereas in other cases happens in response to an injury. The identification of the key factors involved in self-renewal and differentiation pathways is at the top of the agenda of stem cell biologists. Interestingly, a number of factors that govern the fate of adult stem cells also play a role in malignant cell transformation, such as the Wnt cascade, Oct-4, Bmi-1 and Evi1. In addition, rare subpopulations of cancer stem cells were identified for leukemia and other solid tumors. These rare fractions of cancer stem cells are in large part responsible for maintaining the tumor mass, as they have the capacity to self-renew and to generate a high number of progeny via differentiation program. These findings can be considered a major breakthrough in cancer research. Currently, oncologists and stem cell biologists have two main goals: i) the assessment of the consistency of the line that divides adult stem cells and carcinogenesis; ii) to better characterize the biology of cancer stem cells. This new line of investigation may allow for the development of novel therapeutics and cancer diagnostics.

[Laparoscopic cholecystectomy in uremic patients]

The aim of this study was to evaluate the effectiveness of the laparoscopic cholecystectomy performed in two uremic patients with gallstones. From January to July 2004, 15 patients with gallstones underwent to laparoscopic cholecystectomy (LC). Two patients had chronic renal failure on haemodyalisis: a symptomatic fourty-two old woman, which had primitive hyperparathyroidism and primitive hyperaldosteronism, and asymptomatic transplant candidate fifty-five old man. No minor and major complications occurred and both patients were discharged 4 days after LC. Even in uremic patients the L. C. must be the gold standard for the treatment of gallstones both symptomatic and asymptomatic.