Rama Shanker Verma

Bio: Rama Shanker Verma is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Mesenchymal stem cell & Stem cell. The author has an hindex of 30, co-authored 159 publications receiving 3160 citations. Previous affiliations of Rama Shanker Verma include University of Pennsylvania & Thapar University.

Breaking dogma for future therapy using stem cell - Where we have reached?

Abstract: Stem cells (SCs) are functionally immature cells which have the potential to become any cell type upon stimulation. Stem cells have the unique capacity to self-renew, hence are the most promising cell source for tissue regeneration, treating cellular disorders like Parkinson's disease, to replace dead or dysfunctional cells in various traumas. Stem cells are broadly classified into embryonic stem cells (ESC), adult stem cells (ASC), based on their source and induced pluripotent stem cells (iPSC) which are genetically induced by incorporating several nuclear factors such as Sox2, c-myc, Oct4 and nanog, etc1. Pluripotent stem cells are widely used as model system to study embryonic development and cellular differentiation. Stem cells are found in many adult tissues such as epidermis, ocular, muscle, intestine, bone marrow, brain, adipose etc. including insulin-producing beta cells2,3. Growth factors and small molecules control the signals that drive these cells along the different pathways to produce mature cells from stem or progenitor cells. It is the pioneering basic research on the discovery of these signaling pathways for endoderm and pancreatic cells in early development that has paved the way for making laboratory grown beta cells3. A remarkable progress has been made during the past decade specifically, generating insulin producing cells. These cells represent putative beta cells, shown by expression of transcription factors known to control maturation of beta cells that secrete glucose and secretagogue-induced insulin thus restoring normal blood sugar levels after transplantation in diabetic mice4. Two studies4,5 have reported generating insulin-producing cells that resemble normal beta cells from human pluripotent stem cells that share significant functional features with normal human beta cells. This provides a step forward for a potential cell therapy treatment for diabetes. Photoreceptor loss may cause irreversible damage causing blindness in several retinal diseases. Brain- and retina-derived stem cells when transplanted into adult retina were not integrated into the outer nuclear layer and differentiated into new photoreceptors6. The integration of transplanted cells in the retinal region is controlled by ontogentic stage of the cell. Knowledge of the factors which define the differentiation and integration of the precursor cells in the host tissue would facilitate in identifying and enriching the cells suitable for enhancing function in the damaged region6. In the area of dedifferentiation of stem cells, both neural crest stem cells and mesenchymal stem cells (MSCs) from bone marrow have shown some advantage in cellular therapies to replace neurons in various neurological diseases. Neurons derived from hESCs integrate efficiently into brain circuits in vivo7. Blood vessel derived growth factors stimulate neural stem cells to differentiate neurons and this aids the brain repair itself after injury or disease, as in cases of stroke, traumatic brain injury and dementia8. Neuron formation is highly focused option owing to the multiple diseases includes Alzheimer's disease (AD), cerebral palsy, etc. Stem cells can be used as a vehicle to secrete neurotrophins, which are reduced in patients with AD. However, neuronal regeneration is very limited due to the decreased neurogenesis. Embryonic and iPSCs have been successfully used for neuron based regenerative diseases. Recent studies have shown that MSCs from bone marrow do not migrate or differentiate in the MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) treated striatum9. These factors create neuron differentiation a lucrative research option. Vierbuchen et al10 have shown induction of neuronal differentiation in mouse embryonic and postnatal fibroblasts using factors Ascl1, Brn2, and Myt1l. Caiazzo et al11, described a way to reprogram fibroblasts from mouse and human origin into dopaminergic neurons, without going through a pluripotent stage with intact dopaminergic activity. The in vitro differentiation and functionality of neuron differentiation are being studied, but the in vivo usage and therapeutic application are way from seen11. The mechanism of conversion of fibroblasts into neurons is not well studied, Mash1 gene has been shown to play a major role in the differentiation, and initiating immature neuron formation12. Cells of the neural crest origin have been shown to differentiate into neurons and are an easily available source compared to embryonic and mesenchymal lineage. The hair follicles have been shown to harbour pluripotent neural crest stem cells, and these can be differentiated into melanocyte, neuronal cells, adipose cells and other lineages13. Recent studies achieved a step forward in the development of cell-based therapies in other areas such as deafness. In one such study, cells from human embryonic and foetal stem cells identified as a candidate source have been shown to differentiate into auditory neurons that improve auditory-evoked response thresholds14. Similarly, pancreatic progenitor cells derived from hESCs, hold a promising new treatment for diabetes. Bone marrow mesenchymal and haematopoietic stem cells are being studied to develop better repair strategies for the osteoarticular system and blood disorders like thalassaemia. MSCs derived from human adipose tissues engineered to express suicide gene cytosine deaminase :: uracil phosphoribosyltransferase were used as vehicles to treat against gliobastoma cells15. In context to the current work in the issue, Kumar et al16 found stem cell like cells from human skin and hair follicles were characterized for their differentiation potential into melanocytes and neurons. The study focused on the differentiation potential of stem cells from two different sources into melanocytes and neurons. It revealed the enhanced differentiation ability into melanocytes and neurons, which is very promising for the use of candidate cell type in the area of skin regeneration (melanocytes) and also neuron degenerative diseases (neuron). Several research groups have demonstrated the versatility of embryonic stem cells, which can be differentiated into different cell types. Stem cells have the most possible therapeutic use currently in skin regeneration. The source of cells for the purpose revolves around skin graft cells and follicle cells, which are part of the neural crest, that differentiate into the different cell types of the skin, including melanocyte, keratinocyte and skin progenitor cells, etc. Hair follicle is a better source of stem cells for skin regeneration therapy since it has enhanced potential to differentiate into melanocyte17. The epidermis houses skin stem cells owing to the excessive wear and tear experienced by the organ, which help in skin repair. Skin stem cells comprise epidermal stem cells, hair follicle stem cells and melanocyte stem cells. O’ Connor et al18 have shown that the epidermal stem cells can be utilized to form skin grafts for the burn patients. Future direction in this area can include better skin regeneration and that should include rapid proliferating cells with maintenance of stemness, along with regeneration of nerves. Improved culture conditions include supplementing growth factors which induce cell type specific transcription factors that can yield enhanced potential cell type to differentiate into any cell types of skin origin. The formation of neuronal cells in the skin graft might increase the sensation in the regenerated area.

Long range microfluidic shear device for cellular mechanotransduction studies

Abstract: Cells sense external mechanical stimulus and respond to it through mechanotransduction mechanism. Fluid shear stress (FSS) has been found to be an important element among the mechanical stimuli. Recent advancements in microfluidics made mechanotransduction studies possible in near physiological conditions using microfluidic devices. FSS on human cells covers a broad range from very low level experienced due to interstitial flows (0.1 mPa) to very high level in aorta (10 Pa). In the present communication, we have designed a novel microfluidic device which can generate FSS on cells of five different orders with single inflow of fluid which can cover the whole range of physiological fluid shear stresses in one run. The dimensions of the device were calculated taking a resistance model for the micro channels. Flow velocities and wall shear stress were predicted through computer simulation. Shear stress values were analyzed for two different depths of channels and different inlet flow rates ranging from 50 to 0.5 µl/s. FSS was found to increase linearly with inlet flow rate and the stress profile was flatter for lesser depth of channel.

Application of Microbial Toxins for Cancer Therapy

Abstract: The principle of selective targeting of immunotoxins lies on the basis that cancer cells usually have few or specific growth factors/receptors/antigens highly over expressed on their surface. Ligands corresponding to these molecules are conjugated to modified toxins (modified to loss its native function) isolated form variety of bacterial populations. Normal cells either do not express these molecules or express at relatively low number leading to no or minimal adverse effects. The basic mechanism of action of these immunotoxins depends on the toxins employed. In this regard continuous efforts are being made to (i) Identity molecules exclusively expressed in cancer cells, (ii) to improve the specificity and efficacy (iii) reduce size effects of the drugs, (iv) Reduce immunogenicity and (v) to improve better pharmacokinetics for drugs delivery.

Specifics of the methodological approach to the study of nanoparticle impact on human health in the production of non-metallic nanomaterials for construction purposes

Abstract: Minerals samples of mixed-genesis rocks in a finely dispersed state were obtained and studied, namely sand deposit (Kholmogory district) and basalt (Myandukha deposit, Plesetsk district) in Arkhangelsk region. The paper provides the chemical composition data used to calculate the specific mass atomization energy of rocks. The energy parameters of the micro and nano systems of the rock samples – free surface energy and surface activity – were calculated. For toxicological evaluation of the materials obtained, next-generation sequencing (NGS) was used to perform metagenomic analysis which allowed determining the species diversity of microorganisms in the samples under study. It was shown that the sequencing method and metagenomic analysis are applicable and provide good reproducibility for the analysis of the toxicological properties of selected rock samples. The correlation of the surface activity of finely dispersed rock systems and the species diversity of cultivated microorganisms on the raw material was observed.

Osteoblastic cells regulate the haematopoietic stem cell niche

Abstract: Stem cell fate is influenced by specialized microenvironments that remain poorly defined in mammals. To explore the possibility that haematopoietic stem cells derive regulatory information from bone, accounting for the localization of haematopoiesis in bone marrow, we assessed mice that were genetically altered to produce osteoblast-specific, activated PTH/PTHrP receptors (PPRs). Here we show that PPR-stimulated osteoblastic cells that are increased in number produce high levels of the Notch ligand jagged 1 and support an increase in the number of haematopoietic stem cells with evidence of Notch1 activation in vivo. Furthermore, ligand-dependent activation of PPR with parathyroid hormone (PTH) increased the number of osteoblasts in stromal cultures, and augmented ex vivo primitive haematopoietic cell growth that was abrogated by gamma-secretase inhibition of Notch activation. An increase in the number of stem cells was observed in wild-type animals after PTH injection, and survival after bone marrow transplantation was markedly improved. Therefore, osteoblastic cells are a regulatory component of the haematopoietic stem cell niche in vivo that influences stem cell function through Notch activation. Niche constituent cells or signalling pathways provide pharmacological targets with therapeutic potential for stem-cell-based therapies.

Reactive oxygen species in cell signaling

Abstract: Reactive oxygen species (ROS) are generated as by-products of cellular metabolism, primarily in the mitochondria. When cellular production of ROS overwhelms its antioxidant capacity, damage to cellular macromolecules such as lipids, protein, and DNA may ensue. Such a state of “oxidative stress” is thought to contribute to the pathogenesis of a number of human diseases including those of the lung. Recent studies have also implicated ROS that are generated by specialized plasma membrane oxidases in normal physiological signaling by growth factors and cytokines. In this review, we examine the evidence for ligand-induced generation of ROS, its cellular sources, and the signaling pathways that are activated. Emerging concepts on the mechanisms of signal transduction by ROS that involve alterations in cellular redox state and oxidative modifications of proteins are also discussed.

G1 events and regulation of cell proliferation.

Abstract: Cells prepare for S phase during the G1 phase of the cell cycle. Cell biological methods have provided knowledge of cycle kinetics and of substages of G1 that are determined by extracellular signals. Through the use of biochemical and molecular biological techniques to study effects of growth factors, oncogenes, and inhibitors, intracellular events during G1 that lead to DNA synthesis are rapidly being discovered. Many cells in vivo are in a quiescent state (G0), with unduplicated DNA. Cells can be activated to reenter the cycle during G1. Similarly, cells in culture can be shifted between G0 and G1. These switches in and out of G1 are the main determinants of post-embryonic cell proliferation rate and are defectively controlled in cancer cells.

Widespread requirement for Hedgehog ligand stimulation in growth of digestive tract tumours

Abstract: Activation of the Hedgehog (Hh) signalling pathway by sporadic mutations or in familial conditions such as Gorlin's syndrome is associated with tumorigenesis in skin, the cerebellum and skeletal muscle. Here we show that a wide range of digestive tract tumours, including most of those originating in the oesophagus, stomach, biliary tract and pancreas, but not in the colon, display increased Hh pathway activity, which is suppressible by cyclopamine, a Hh pathway antagonist. Cyclopamine also suppresses cell growth in vitro and causes durable regression of xenograft tumours in vivo. Unlike in Gorlin's syndrome tumours, pathway activity and cell growth in these digestive tract tumours are driven by endogenous expression of Hh ligands, as indicated by the presence of Sonic hedgehog and Indian hedgehog transcripts, by the pathway- and growth-inhibitory activity of a Hh-neutralizing antibody, and by the dramatic growth-stimulatory activity of exogenously added Hh ligand. Our results identify a group of common lethal malignancies in which Hh pathway activity, essential for tumour growth, is activated not by mutation but by ligand expression.