Marrow changes and reduced proliferative capacity of mesenchymal stromal cells from patients with "no-option" critical limb ischemia; observations on feasibility of the autologous approach from a clinical trial.

BACKGROUND AIMS: Approximately 1 in 3 patients with critical limb ischemia (CLI) are not suitable for surgical or endovascular revascularization. Those "no-option" patients are at high risk of amputation and death. Autologous bone marrow mesenchymal stromal cells (MSCs) may provide a limb salvage option. In this study, bone marrow characteristics and expansion potentials of CLI-derived MSCs produced during a phase 1b clinical trial were compared with young healthy donor MSCs to determine the feasibility of an autologous approach. Cells were produced under Good Manufacturing Practice conditions and underwent appropriate release testing. METHODS: Five bone marrow aspirates derived from patients with CLI were compared with six young healthy donor marrows in terms of number of colony-forming units-fibroblast (CFUF) and mononuclear cells. The mean population doubling times and final cell yields were used to evaluate expansion potential. The effect of increasing the volume of marrow on the CFUF count and final cell yield was evaluated by comparing 5 CLI-derived MSCs batches produced from a targeted 30 mL of marrow aspirate to five batches produced from a targeted 100 mL of marrow. RESULTS: CLI-derived marrow aspirate showed significantly lower numbers of mononuclear cells with no difference in the number of CFUFs when compared with healthy donors' marrow aspirate. CLI-derived MSCs showed a significantly longer population doubling time and reduced final cell yield compared with young healthy donors' MSCs. The poor growth kinetics of CLI MSCs were not mitigated by increasing the bone marrow aspirate from 30 to 100 mL. CONCLUSIONS: In addition to the previously reported karyotype abnormalities in MSCs isolated from patients with CLI, but not in cells from healthy donors, the feasibility of autologous transplantation of bone marrow MSCs for patients with no-option CLI is further limited by the increased expansion time and the reduced cell yield.

Validation of ERICVA Risk Score as a Predictor of One Year Amputation-Free Survival of Patients with Critical Limb Ischemia.

BACKGROUND: The ERICVA score was derived to predict amputation-free survival in patients with critical limb ischemia (CLI). It may be a useful tool to stratify patients in trials of novel interventions to treat CLI but, as yet, it has not been externally validated. METHODS: A prospective database of CLI patients was developed during prescreening of patients for a phase 1 stem cell therapy clinical trial. The primary outcome was amputation free survival (AFS) at 1 year. Both the full ERICVA scale (11 parameters) and simplified ERICVA scale (5 parameters) were validated. Data analysis was performed by calculation of the area under the receiver operating characteristic (ROC) curve examining the predictive value of the scores. The Chi-square test was used to examine the association between risk group and one-year AFS and the cumulative survival of the three risk groups was compared using Kaplan Meier survival curves. RESULTS: A series of 179 CLI patients were included in the analysis. The Chi-square test of independence showed a significant association between the risk group (high, medium and low) and one-year AFS outcome (P = 0.0007). Kaplan-Meier survival curve showed significant difference in one-year AFS between the three risk groups (log-rank P < 0.001). The area under the curve (AUC) was found to be 0.63 and 0.61 for the full and simplified score, respectively. The sensitivity of the full score was 0.44 with specificity of 0.84. The simplified score had a sensitivity of 0.28 and specificity of 0.92. CONCLUSION: The ERICVA risk score system was found to have a fair validity but cannot be considered reliable as a single predictor of one year AFS of CLI patients. The simplified score had an AUC almost identical to the full score and can accordingly replace the full score.

Survival/Adaptation of Bone Marrow-Derived Mesenchymal Stem Cells After Long-Term Starvation Through Selective Processes.

After in vivo transplantation, mesenchymal stem cells (MSC) face an ischemic microenvironment, characterized by nutrient deprivation and reduced oxygen tension, which reduces their viability and thus their therapeutic potential. Therefore, MSC response to models of in vitro ischemia is of relevance for improving their survival and therapeutic efficacy. The aim of this study was to understand the survival/adaptive response mechanism that MSC use to respond to extreme culture conditions. Specifically, the effect of a long-term starvation on human bone marrow (hBM)-derived MSC cultured in a chemically defined medium (fetal bovine serum-free [SF] and human SF), either in hypoxic or normoxic conditions. We observed that hBM-MSC that were isolated and cultured in SF medium and subjected to a complete starvation for up to 75 days transiently changed their behavior and phenotype. However, at the end of that period, hBM-MSC retained their characteristics as determined by their morphology, DNA damage resistance, proliferation kinetic, and differentiation potential. This survival mode involved a quiescent state, confirmed by increased expression of cell cycle regulators p16, p27, and p57 and decreased expression of proliferating cell nuclear antigen (PCNA), Ki-67, mTOR, and Nanog. In addition, Jak/STAT (STAT6) antiapoptotic activity selected which cells conserved stemness and that supported metabolic, bioenergetic, and scavenging requirements. We also demonstrated that hBM-MSC exploited an autophagic process which induced lipid ß-oxidation as an alternative energy source. Priming MSC by concomitant starvation and culture in hypoxic conditions to induce their quiescence would be of benefit to increase MSC survival when transplanted in vivo. Stem Cells 2019;37:813-827.

Autologous bone marrow mesenchymal stromal cell therapy for "no-option" critical limb ischemia is limited by karyotype abnormalities.

BACKGROUND: Critical limb ischemia (CLI) is the most severe manifestation of peripheral vascular disease. Revascularization is the preferred therapy, but it is not achievable in 25%-40% of patients due to diffuse anatomic distribution of the disease or medical comorbidities. No-option CLI represents an unmet medical need. Mesenchymal stromal cells (MSCs) may provide salvage therapy through their angiogenic and tissue-trophic properties. This article reports a phase 1b clinical study examining the safety and feasibility of intramuscular transplantation of autologous bone-marrow MSCs for patients with no-option CLI. METHODS: Twelve patients were enrolled in the clinical trial, and nine proceeded to bone marrow aspiration and culture expansion of MSCs. RESULTS: A high rate of karyotype abnormality (>30%) was detected in the produced cell batches, resulting in failure of release for clinical administration. Four patients were treated with the investigational medicinal product (IMP), three with a low dose of 20 × 106 MSCs and one with a mid-dose of 40 × 106 MSCs. There were no serious adverse events related to trial interventions, including bone marrow aspiration, IMP injection or therapy. CONCLUSIONS: The results of this trial conclude that an autologous cell therapy approach with MSCs for critical limb ischemia is limited by the high rate of karyotype abnormalities.

TNF-α/IL-1ß-licensed mesenchymal stromal cells promote corneal allograft survival via myeloid cell-mediated induction of Foxp3+ regulatory T cells in the lung.

Mesenchymal stromal cells (MSCs) have shown promise as a therapy for immune-mediated disorders, including transplant rejection. Our group previously demonstrated the efficacy of pretransplant, systemic administration of allogeneic but not syngeneic MSCs in a rat cornea transplant model. The aim of this study was to enhance the immunomodulatory capacity of syngeneic MSCs. In vitro, MSCs licensed with TNF-α/IL-1ß (MSCsTNF-α/IL-1ß) suppress syngeneic lymphocyte proliferation via NO production. In vivo, when administered post-transplantation, nonlicensed syngeneic MSCs improved graft survival from 0 to 50% and MSCsTNF-α/IL-1ß, in an NO-dependent manner, improved survival to 70%. Improved survival was associated with increased CD4+CD25+forkhead box P3+ regulatory T (Treg) cells and decreased proinflammatory cytokine expression in the draining lymph node. MSCsTNF-α/IL-1ß demonstrated a more potent immunomodulatory capacity compared with nonlicensed MSCs, promoting an immune-regulatory CD11b+B220+ monocyte/macrophage population and significantly expanding Treg cells in the lungs and spleen. Ex vivo, we observed that lung-derived myeloid cells act as intermediaries of MSC immunomodulatory function. MSC-conditioned myeloid cells suppressed stimulated lymphocyte proliferation and promoted expansion of Treg cells from naive lymphocytes. This work illustrates how syngeneic MSC therapy can be enhanced by licensing and optimization of timing strategies and further highlights the important role of myeloid cells in mediating MSC immunomodulatory capacity.-Murphy, N., Treacy, O., Lynch, K., Morcos, M., Lohan, P., Howard, L., Fahy, G., Griffin, M. D., Ryan, A. E., Ritter, T. TNF-α/IL-1ß-licensed mesenchymal stromal cells promote corneal allograft survival via myeloid cell-mediated induction of Foxp3+ regulatory T cells in the lung.

Cell viability in three ex vivo rat models of spinal cord injury.

Spinal cord injury (SCI) is a devastating disorder that has a poor prognosis of recovery. Animal models of SCI are useful to understand the pathophysiology of SCI and the potential use of therapeutic strategies for human SCI. Ex vivo models of central nervous system (CNS) trauma, particularly mechanical trauma, have become important tools to complement in vivo models of injury in order to reproduce the sequelae of human CNS injury. Ex vivo organotypic slice cultures (OSCs) provide a reliable model platform for the study of cell dynamics and therapeutic intervention following SCI. In addition, these ex vivo models support the 3R concept of animal use in SCI research - replacement, reduction and refinement. Ex vivo models cannot be used to monitor functional recovery, nor do they have the intact blood supply of the in vivo model systems. However, the ex vivo models appear to reproduce many of the post traumatic events including acute and secondary injury mechanisms. Several well-established OSC models have been developed over the past few years for experimental spinal injuries ex vivo in order to understand the biological response to injury. In this study, we investigated cell viability in three ex vivo OSC models of SCI: stab injury, transection injury and contusion injury. Injury was inflicted in postnatal day 4 rat spinal cord slices. Stab injury was performed using a needle on transverse slices of spinal cord. Transection injury was performed on longitudinal slices of spinal cord using a double blade technique. Contusion injury was performed on longitudinal slices of spinal cord using an Infinite Horizon impactor device. At days 3 and 10 post-injury, viability was measured using dual staining for propidium iodide and fluorescein diacetate. In all ex vivo SCI models, the slices showed more live cells than dead cells over 10 days in culture, with higher cell viability in control slices compared with injured slices. Although no change in cell viability was observed between time-points in stab- and contusion-injured OSCs, a reduction in cell viability was observed over time in transection-injured OSCs. Taken together, ex vivo SCI models are a useful and reliable research tool that reduces the cost and time involved in carrying out animal studies. The use of OSC models provides a simple way to study the cellular consequences following SCI, and they can also be used to investigate potential therapeutics regimes for the treatment of SCI.

Long QT Syndrome: Genetics and Future Perspective.

Long QT syndrome (LQTS) is an inherited primary arrhythmia syndrome that may present with malignant arrhythmia and, rarely, risk of sudden death. The clinical symptoms include palpitations, syncope, and anoxic seizures secondary to ventricular arrhythmia, classically torsade de pointes. This predisposition to malignant arrhythmia is from a cardiac ion channelopathy that results in delayed repolarization of the cardiomyocyte action potential. The QT interval on the surface electrocardiogram is a summation of the individual cellular ventricular action potential durations, and hence is a surrogate marker of the abnormal cellular membrane repolarization. Severely affected phenotypes administered current standard of care therapies may not be fully protected from the occurrence of cardiac arrhythmias. There are 17 different subtypes of LQTS associated with monogenic mutations of 15 autosomal dominant genes. It is now possible to model the various LQTS phenotypes through the generation of patient-specific induced pluripotent stem cell-derived cardiomyocytes. RNA interference can silence or suppress the expression of mutant genes. Thus, RNA interference can be a potential therapeutic intervention that may be employed in LQTS to knock out mutant mRNAs which code for the defective proteins. CRISPR/Cas9 is a genome editing technology that offers great potential in elucidating gene function and a potential therapeutic strategy for monogenic disease. Further studies are required to determine whether CRISPR/Cas9 can be employed as an efficacious and safe rescue of the LQTS phenotype. Current progress has raised opportunities to generate in vitro human cardiomyocyte models for drug screening and to explore gene therapy through genome editing.

Biodistribution and retention of locally administered human mesenchymal stromal cells: Quantitative polymerase chain reaction-based detection of human DNA in murine organs.

BACKGROUND: Determining the distributive fate and retention of a cell therapy product after administration is an essential part of characterizing it's biosafety profile. Therefore, regulatory guidelines stipulate that biodistribution assays are a requirement prior to advancing a cell therapy to the clinic. Here the development of a highly sensitive quantitative polymerase chain reaction (qPCR)-based method of tracking the biodistribution and retention of human mesenchymal stromal cells (hMSCs) in mice, rats or rabbits is described. METHODS: A primer-probe-based qPCR assay was developed to detect and quantify human Alu sequences in a heterogeneous sample of human DNA (hDNA) and murine DNA from whole organ genomic DNA extracts. The assay measures the amount of genomic hDNA by amplifying a 31-base pair sequence of the human Alu (hAlu) repeat sequence, thus enabling the detection of 0.1 human cells in 1.5 × 106 heterogeneous cells. RESULTS: Using this assay we investigated the biodistribution of 3 × 105 intramuscularly injected hMSCs in Balb/c nude mice. Genomic DNA was extracted from murine organs and hAlu sequences were quantified using qPCR analysis. After 3 months, hDNA ranging from 0.07%-0.58% was detected only at the injection sites and not in the distal tissues of the mice. DISCUSSION: This assay represents a reproducible, sensitive a method of detecting hDNA in rodent and lapine models. This manuscript describes the method employed to generate preclinical biodistribution data that was accepted by regulatory bodies in support of a clinical trial application.

Interventional EUS Using a Flexible 19-Gauge Needle: An International Multicenter Experience in 162 Patients.

BACKGROUND AND AIMS: To facilitate access for interventional EUS, flexible (nitinol) 19-G needles have been introduced to permit needle puncture even when the echoendoscope is in an angulated position, such as in the second part of the duodenum. The aims of the study were to evaluate the performance of a flexible 19-G needle during interventional EUS procedures and compare outcomes when the echoendoscope was in the straight versus angulated position. METHODS: A retrospective review was undertaken of 162 consecutive patients that underwent a variety of interventional EUS procedures with a flexible 19-G needle across five centers. Patients were subdivided into categories (straight or angulated) depending on the echoendoscope position used for obtaining access to the area of interest (Fig. 1). Fig. 1 Flexible 19-G needle design. a The needle is able to exit the sheath despite the rotated position. b The needle beveled needle tip RESULTS: In the entire cohort, needle-specific technical success was achieved in 93.2 %, procedural success in 85.2 %, and overall clinical success in 76.5 % of cases at a mean follow-up of 3.1 months. Needle-specific technical success was similar between the straight and angulated cohorts (94.0 vs. 91.2 %, p = 0.74). Procedural success (86.7 vs. 77.2 %, p = 0.05), and rate of clinical success was similar between the cohorts (83.3 vs. 86.4 %, p = 0.79), respectively. Overall adverse events were noted in 14.2 % of patients with no difference between the straight and angulated cohorts (p = 0.48). CONCLUSIONS: This study demonstrates equivalent technical success, clinical success and safety of using a flexible 19-G needle in straight and angulated endoscope positions for interventional EUS. Therefore, a flexible needle may be considered where an angulated echoendoscope position is encountered.

Extracellular Vesicles, Cell-Penetrating Peptides and miRNAs as Future Novel Therapeutic Interventions for Parkinson's and Alzheimer's Disease.

Neurodegeneration is hallmarked by the progressive loss of dopaminergic neurons and/or a significant increase in protein aggregates in the brain. Neurodegenerative diseases are a leading cause of death worldwide with over 15 million people currently suffering from either Parkinson's disease (PD) or Alzheimer's disease (AD). PD is often characterized by both motor and non-motor symptoms, including muscle rigidity, tremors and bradykinesia, with AD displaying symptoms of confusion and dementia. The current mainstay of therapeutics includes pharmacological approaches such as levodopa to replace dopamine in PD patients, deep brain stimulation in affected regions of the brain and physical therapy. However, these treatments are typically not disease-modifying, though they do help at least for some time with symptom management. These treatments often also fail due to their inability to cross the blood-brain barrier. There is a need to develop new strategies to target neurodegeneration in an ever-ageing population. First, we review the current PD and AD treatments and their limitations. Second, we review the current use of extracellular vesicles (EVs), cell-penetrating peptides (CPPs) and miRNAs as neuroprotective agents. Finally, we discuss the possibility of exploiting these as a combinatory therapeutic, alongside some potential drawbacks.

Sternal wound care to prevent infections in adult cardiac surgery patients.

Sternal wound infection post-cardiac surgery is a serious complication that can lead to increased length of stay, substantial financial impact, and increased mortality. The occurrence of sternal wound infections has been reported from 0.4% to 4% of postoperative cardiac surgeries. It is imperative that every heart surgery program implements the best practice to prevent the detrimental effects of sternal wound infections. In an effort to improve the cardiothoracic (CT) surgery program in a community hospital, a decision was made to create a specialty floor including specialized nurses to care for open-heart surgery patients. In October 2010, a group of these nurses formed a working committee to explore ways to improve the overall care of our CT surgery patients. A vision and purpose for this committee were identified: (1) update and improve practice for CT surgery patients utilizing evidence-based standards, (2) successfully disseminate this information to all staff caring for the CT surgery patients, and (3) evaluate the impact of any practice changes on patient outcomes. An initial focus for the committee was to standardize sternal wound care among all staff members on the cardiovascular floors, cardiac care unit, and progressive care unit.

Lentiviral Vectors Delivered with Biomaterials as Therapeutics for Spinal Cord Injury.

Spinal cord injury (SCI) is a devastating trauma that can cause permanent disability, life-long chronic issues for sufferers and is a big socioeconomic burden. Regenerative medicine aims to overcome injury caused deficits and restore function after SCI through gene therapy and tissue engineering approaches. SCI has a multifaceted pathophysiology. Due to this, producing therapies that target multiple different cellular and molecular mechanisms might prove to be a superior approach in attempts at regeneration. Both biomaterials and nucleic acid delivery via lentiviral vectors (LVs) have proven to promote repair and restoration of function post SCI in animal models. Studies indicate that a combination of biomaterials and LVs is more effective than either approach alone. This review presents studies supporting the use of LVs and LVs delivered with biomaterials in therapies for SCI and summarises methods to combine LVs with biomaterials for SCI treatment. By summarising this knowledge this review aims to demonstrate how LV delivery with biomaterials can augment/compliment both LV and biomaterial therapeutic effects in SCI.

Derivation of iPSC lines from two patients with autism spectrum disorder carrying NRXN1α deletion (NUIGi041-A, NUIG041-B; NUIGi045-A) and one sibling control (NUIGi042-A, NUIGi042-B).

NRXN1 encodes thousands of splicing variants categorized into long NRXN1α, short NRXN1ß and extremely short NRXN1γ, which exert differential roles in neuronal excitation/inhibition. NRXN1α deletions are common in autism spectrum disorder (ASD) and other neurodevelopmental/neuropsychiatric disorders. We derived induced pluripotent stem cells (iPSCs) from one sibling control and two ASD probands carrying NRXN1α+/-, using non-integrating Sendai viral method. All iPSCs highly expressed pluripotency markers and could be differentiated into ectodermal/mesodermal/endodermal cells. The genotype and karyotype of the iPSCs were validated by whole genome SNP array. The availability of the iPSCs offers an opportunity for understanding NRXN1α function in human neurons and in ASD.

Derivation of four iPSC lines from a male ASD patient carrying a deletion in the middle coding region of NRXN1α gene (NUIGi039-A and NUIGi039-B) and a male sibling control (NUIGi040-A and NUIGi040-B).

NRXN1 deletions are commonly found in autism spectrum disorder (ASD) and other neurodevelopmental/neuropsychiatric disorders. Derivation of induced pluripotent stem cells (iPSCs) from different diseases involving different deletion regions are essential, as NRXN1 may produce thousands of splicing variants. We report here the derivation of iPSCs from a sibling control and an ASD proband carrying de novo heterozygous deletions in the middle region of NRXN1, using a non-integrating Sendai viral kit. The genotype and karyotype of the iPSCs were validated by whole genome SNP array. All iPSC lines highly expressed pluripotency markers and could be differentiated into three germ layers.

Ex Vivo Rat Transected Spinal Cord Slices as a Model to Assess Lentiviral Vector Delivery of Neurotrophin-3 and Short Hairpin RNA against NG2.

The failure of the spinal cord to regenerate can be attributed both to a lack of trophic support for regenerating axons and to upregulation of inhibitory factors such as chondroitin sulphate proteoglycans including NG2 following injury. Lentiviral vector-mediated gene therapy is a possible strategy for treating spinal cord injury (SCI). This study investigated the effect of lentiviral vectors expressing Neurotrophin-3 (NT-3) and short-hairpin RNA against NG2 (NG2 sh) to enhance neurite outgrowth in in vitro and ex vivo transection injury models. Conditioned medium from cells transduced with NT-3 or shNG2 lentiviruses caused a significant increase in neurite length of primary dorsal root ganglia neurons compared to the control group in vitro. In an ex vivo organotypic slice culture (OSC) transduction with Lenti-NT-3 promoted axonal growth. Transducing OSCs with a combination of Lenti-NT-3/NG2 sh lead to a further increase in axonal growth but only in injured slices and only within the region adjacent to the site of injury. These findings suggest that the combination of lentiviral NT-3 and NG2 sh reduced NG2 levels and provided a more favourable microenvironment for neuronal regeneration after SCI. This study also shows that OSCs may be a useful platform for studying glial scarring and potential SCI treatments.

Derivation of familial iPSC lines from three patients with retinitis pigmentosa carrying an autosomal dominant RPE65 mutation (NUIGi027-A, NUIGi028-A, NUIGi029-A).

Retinitis Pigmentosa (RP) is an inherited disorder of retinal degeneration with progressive loss of rod and cone photoreceptors. RPE65 is a gene encoding the trans-cis isomerase which is essential for the classical visual cycle. While most RPE65 mutations associated with RP have been reported as autosome, an Irish c.1430A > G (p.D477G) mutation is the first case reported to cause dominantly inherited RP. In this study, we used the non-integrational Sendai virus to generate induced pluripotent stem cell (iPSC) lines carrying the c.1430A > G (p.D477G) mutation from three familial RP patients.

Derivation of two iPSC lines from a sporadic ASD patient (NUIGi033-A) and a paternal control (NUIGi034-A).

Hundreds of rare risk factors have been identified for ASD, however, the underlying causes for ~70% of sporadic cases are unknown. Sporadic ASD models are thus essential for validating phenotypic commonality and drug suitability to the majority of patients. Here, we derived induced pluripotent stem cells (iPSCs) from one sporadic ASD child and one paternal control, using non-integrating Sendai viral methods. The iPSCs strongly expressed pluripotency markers and could be differentiated into three germ layers. Their normal karyotype was validated by genome SNP array. The availability of sporadic ASD-derived iPSCs offers an opportunity for phenotypic comparison with genetic ASD models.

Derivation of iPSC lines from three young healthy donors of Caucasian origin (NUIGi035-A; NUIGi036-A; NUIGi037-A).

The induced pluripotent stem cell (iPSC) technology has offered an unprecedented opportunity for disease modelling and drug discovery. Here we used non-integrating Sendai viral method and derived iPSCs from three young healthy Caucasian donors. All iPSCs expressed pluripotency markers highly and could be differentiated into three germ lineages. They possess normal karyotype which was confirmed by whole genome SNP array. The availability of the healthy control iPSCs offers an opportunity for phenotypic comparison and genome editing for a variety of diseases.

Gene-eluting stents: adenovirus-mediated delivery of eNOS to the blood vessel wall accelerates re-endothelialization and inhibits restenosis.

Drug-eluting stents for coronary artery disease results in inhibition of smooth muscle cell (SMC) and endothelial cells which may increase the risk of stent thrombosis. In this study, we attempted to enhance re-endothelialization of deployed stents while simultaneously inhibiting intimal hyperplasia by overexpression of endothelial nitric oxide synthase (eNOS) delivery in the vasculature using an adenovirus gene-eluting stent. Re-endothelialization was significantly greater in vessels obtained from normocholesterolemic animals at day 14 (85.34% +/- 7.38 versus 62.66% +/- 10.49; P < 0.05) and day 28 (91.1% +/- 10 versus 63.1% +/- 22; P < 0.05) and hypercholesterolemic animals (96.97% +/- 3.2 versus 28.33% +/- 38.76; P < 0.05) at day 28 with AdeNOS-eluting stents. At day 28, there was a significant increase in the lumen size [AdeNOS 2.73 mm(2) +/- 1.18, AdbetaGal 0.98 mm(2) +/- 0.98, phosphorylcholine (PC) 1.87 mm(2) +/- 1.18; P < 0.05], and a significant reduction in neointimal formation (AdeNOS 2.32 mm(2) +/- 1.13, AdbetaGal 3.73 mm(2) +/- 0.95, PC 3.2 mm(2) +/- 0.94; P < 0.05), and percent restenosis (AdeNOS 45.23 +/- 20.81, AdbetaGal 79.6 +/- 20.31, PC 70.16 +/- 22.2; P < 0.05) in AdeNOS-stented vessels in comparison with controls from hypercholesterolemic animals, assessed by morphometry and quantitative coronary angiography (AdeNOS 15.95% +/- 7.63, AdbetaGal 56.9% +/- 38.6, PC 58 +/- 34.6; P < 0.05). Stent-based delivery of AdeNOS results in enhanced endothelial regeneration and reduction in neointimal formation as compared with controls. This seems to be a promising treatment strategy for preventing in-stent restenosis (ISR) while simultaneously reducing the risk of stent thrombosis.

Effects of plating density and culture time on bone marrow stromal cell characteristics.

OBJECTIVE: Bone marrow stromal cells (MSC) are multipotent adult stem cells that have emerged as promising candidates for cell therapy in disorders including cardiac infarction, stroke, and spinal cord injury. While harvesting methods used by different laboratories are relatively standard, MSC culturing protocols vary widely. This study is aimed at evaluating the effects of initial plating density and total time in culture on proliferation, cell morphology, and differentiation potential of heterogeneous MSC cultures and more homogeneous cloned subpopulations. MATERIALS AND METHODS: Rat MSC were plated at 20, 200, and 2000 cells/cm(2) and grown to 50% confluency. The numbers of population doublings and doubling times were determined within and across multiple passages. Changes in cell morphology and differentiation potential to adipogenic, chondrogenic, and osteogenic lineages were evaluated and compared among early, intermediate, and late passages, as well as between heterogeneous and cloned MSC populations. RESULTS: We found optimal cell growth at a plating density of 200 cells/cm(2). Cultures derived from all plating densities developed increased proportions of flat cells over time. Assays for chondrogenesis, osteogenesis, and adipogenesis showed that heterogeneous MSC plated at all densities sustained the potential for all three mesenchymal phenotypes through at least passage 5; the flat subpopulation lost adipogenic and chondrogenic potential. CONCLUSION: Our findings suggest that the initial plating density is not critical for maintaining a well-defined, multipotent MSC population. Time in culture, however, affects cell characteristics, suggesting that cell expansion should be limited, especially until the specific characteristics of different MSC subpopulations are better understood.