Antonia Aránega

Actinomycin D treatment leads to differentiation and inhibits proliferation in rhabdomyosarcoma cells

Human embryonal cell line RD is derived from rhabdomyosarcoma, a tumor of childhood that arises from rhabdomyoblasts probably arrested somewhere along their pathway to maturation. Because actinomycin D is a drug of choice in the treatment of rhabdomyosarcomas, and because it has been used to induce differentiation as an alternative therapy for myeloproliferative syndromes, we treated RD cells with different concentrations of actinomycin D and evaluated the effects on growth and differentiation. Actinomycin D treatment in vitro caused time- and dose-dependent growth inhibition. Interestingly, RD cells treated with low doses (2.85 and 5.7 nmol/L) of actinomycin D for 6 days showed morphologic and phenotypic differentiation, with increased expression of desmin, alpha-actinin, and tropomyosin. However, treatment with 11.4 nmol/L actinomycin D strongly inhibited growth and had cytotoxic effects that prevented the cells from attaining myogenic differentiation. We conclude that exposure of this human embryonal rhabdomyosarcoma cell line to low concentrations of actinomycin D released the neoplastic cells from their blockade, allowing them to recover normal myogenic development. We suggest a potential role for differentiation therapy in the treatment of rhabdomyosarcomas.

Detection of Creatine Kinase Isoenzymes as Tumoral Markers of Rhabdomyosarcoma

We analyzed the expression profile of isoenzymatic fractions of creatine phosphokinase (EC 2.7.3.2) isotypes MM, MB and BB in three cell lines derived from embryonic rhabdomyosarcomas and a normal counterpart cell line. Electrophoretic data showed that the BB fraction was consistently expressed de novo, in contrast with its counterpart in normal tissue. The BB fraction may serve as new tumoral marker for the diagnosis of rhabdomyosarcoma. In addition, the appearance of macrocreatine kinase type-1 in this type of neoplasm may serve to reinforce the diagnosis when rhabdomyosarcoma is suspected.

Treatment of Heart Disease: Use of Transdifferentiation Methodology for Reprogramming Adult Stem Cells

Despite significant progress in medical research, cardiovascular diseases (CVDs) continue to be the largest contributors to morbidity and mortality in both developed and developing countries. The discovery of multipotent cell populations in adult tissues has opened up new therapeutic possibilities for diseases that cannot be successfully treated by conventional medical therapies. The scientific community is developing new methods to improve clinical outcomes, including the transplantation of stem cells in a pre-differentiated state. In vivo studies have demonstrated the capacity of these cells to differentiate into another cell type through the triggering of a genetic switch by pathological or inductive conditions. This process, whereby one cell type committed to and progressing along a specific developmental lineage switches into another cell type of a different lineage, is designated transdifferentiation and takes place in tissues generated from neighbouring regions during normal embryonic development. In this chapter, we review the current methods of transdifferentiation including guided cardiopoiesis, cellular extracts, co-culture techniques, viral vectors, hyperpolarization, among others.

Therapeutic Approaches in Regenerative Medicine of Cardiovascular Diseases: From Bench to Bedside

Despite significant progress in medical research, which has led to lower infant mortality rates and increased life expectancy, cardiovascular diseases (CVDs) continue to be the largest contributors of morbidity and mortality in both developed and developing countries. In fact, they are predicted to be the leading cause of death by 2020 and responsible for 13.4% of total world-wide deaths by 2030. These diseases have a multifactorial origin, notably nonmodifiable cardiovascular risk factors (CRFs) such as age, sex, race or family history, and modifiable CRFs, including smoking, hypertension, hypercholesterolemia, diabetes mellitus or hypertriglyceridemia (Picariello et al., 2011; Glynn & Rosner, 2005). Currently, there are no effective treatments available for many degenerative diseases caused by the death or malfunction of specific cells. In this regard, the main physiopathology of CVDs is related to ischaemic heart disease, and approximately two-thirds of patients surviving an acute myocardial infarction (AMI) are left with debilitating congestive heart failure. AMI causes apoptosis and necrosis of cardiomyocytes, a specialized and differentiated cell population responsible for ventricular contraction, the main event of cardiac function. The low selfrenewal rate of these cells (~0.06% of the total population of cardiomyocytes under normal conditions) produces, in cases of acute stress, the ventricular remodelling of non-ischaemic myocardium with scar formation, increasing the likelihood of a new crisis, progressive ventricular dilatation and heart failure, ending in death (Torella et al., 2007). Organ transplantation is an appropriate therapeutic strategy for patients who have suffered end-stage heart failure and are unresponsive to conventional therapy but has drawbacks related to donor incompatibility, which can lead to rejection and eventually to Graft Versus