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Among additive manufacturing (AM) techniques, laser or electron beam based processes have been widely investigated for metallic implants. Despite the potential in manufacturing of patient-specific biomedical implants, 3D inkjet powder printing (3DLIPP, a variant of AM) of biomaterials is still in its infancy, as little is known quantitatively about the transient process physics and dynamics. An equally important challenge has been the ink formulation to manufacture biomaterials with reliable mechanical properties and desired biocompatibility. We have developed, for the very first time, the theoretical foundation and experimental formulation of a unique process strategy involving the `on-demand' delivery of a novel in situ polymerisable acrylic ink system to print a model biomaterial, Ti-6Al-4V. The post-ejection in-flight dynamics of ink droplets have been captured in situ by employing high speed stroboscopic shadowgraphy, to quantitatively estimate the dimensionless numbers of fluid physics for `printability' assessment. Washburn model was adapted extensively to quantify the capillary ink infiltration time in porous powder bed of finite thickness. On the other hand, particle tracking mode in diffusing wave spectroscopy (DWS) was exploited to analyse the timescale for effective binding of powder particles during in situ polymerisation. The clinically relevant combination of 3D porous architecture with 98.4% interconnectivity among 10-40 mu m pores together with modest combination of elastic modulus (4 GPa) and strength reliability (Weibull modulus similar to 8.1) establish the potential of inkjet printed Ti-6Al-4V as cortical bone analogue. A better cell attachment, viability, cytoskeletal spreading with pronounced proliferation of murine fibroblasts and pre-osteoblasts on 3DIJPP Ti-6Al-4V, when benchmarked against the metallurgically processed (commercial) or selective laser melted (SLM) Ti-6Al-4V, has been demonstrated, in vitro. The enhanced cellular activities on the 3DIJPP Ti-6Al-4V was explained in terms of an interplay among the elastic stiffness, surface roughness and wettability against the same benchmarking. It is conceived that the quantitative understanding of the integrated process physics and dynamics to print Ti-6Al-4V with reliable mechanical properties together with better cytocompatibility can lead to a paradigm shift in adapting the scalable 3DIJPP for manufacturing of metallic biomaterials.

Accelerating the clearance of intracellular protein aggregates through elevation of autophagy represents a viable approach for the treatment of neurodegenerative diseases. In our earlier report, we have demonstrated the enhanced degradation of mutant huntingtin protein aggregates through autophagy process induced by europium hydroxide nanorods [EHNs: Eu(III)(OH)3], but the underlying molecular mechanism of EHNs mediated autophagy was unclear. The present report reveals that EHNs induced autophagy does not follow the classical AKT-mTOR and AMPK signaling pathways. The inhibition of ERK1/2 phosphorylation using the specific MEK inhibitor U0126 partially abrogates the autophagy as well as the clearance of mutant huntingtin protein aggregates mediated by EHNs suggesting that nanorods stimulate the activation of MEK/ERK1/2 signaling pathway during autophagy process. In contrast, another mTOR-independent autophagy inducer trehalose has been found to induce autophagy without activating ERK1/2 signaling pathway. Interestingly, the combined treatment of EHNs and trehalose leads to more degradation of mutant huntingtin protein aggregates than that obtained with single treatment of either nanorods or trehalose. Our results demonstrate the rational that further enhanced clearance of intracellular protein aggregates, needed for diverse neurodegenerative diseases, may be achieved through the combined treatment of two or more autophagy inducers, which stimulate autophagy through different signaling pathways.

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that offer a promising outcome in the field of regenerative medicine. MSCs are present in various tissues including bone marrow, fat, skin, and placenta. The interest in clinical application of these mesoderm-derived MSCs is primarily fueled by their high self-renewal capacity and multipotency. Although, early studies indicated limited differentiation capacity of MSCs into same cell lineages from which they were isolated, subsequent investigations showed differentiation potential into other cell types of mesoderm origin including osteoblasts, adipocytes, fibroblasts, cardiomyocytes, and chondrocytes. Furthermore, MSCs exhibit a remarkable feature of transdifferentiation into ectodermal, neuroectodermal, and endodermal cells, phenomena referred to as ‘stem cell plasticity’. This opened the possibility of clinical applications of MSCs in the regeneration of other tissues like corneal reconstruction, treatment of acute lung injury, oral mucosal regeneration, homing of MSCs for regeneration at sites of injury etc. Though several evidence have accrued demonstrating this phenomenon, there is still a gap in understanding the molecular mechanism of such transitions which will be important to efficiently control the process. Interestingly, the process can be drawn a parallel with the Mesenchymal to Epithelial Transitions (MET) that takes place inside the body during embryonic development or certain pathophysiological conditions. In this review, a brief attempt is first made to understand the evidence of MSC transdifferentiation based on the current knowledge about MET. We then specifically focus on systematic presentation and analysis of the microenvironment factors involved in MSC transdifferentiation to epithelial lineages which would have applications in regenerative medicine.

Curcumin, because of its distinguishing ability to inhibit activation of transcription factor linked to chemoresistance and drug transporters, is now being co-administered with various potent anti-cancer drugs. In the present study, we report on such potentiating capabilities of curcumin in anti-angiogenic cancer therapy. With a view to simultaneously deliver curcumin and doxorubicin to tumor vasculature in anti-angiogenic cancer therapy, herein we report on the design & synthesis of a tumor vasculature targeting pegylated RGDK-lipopeptide. We show that curcumin & doxorubicin co-encapsulated within the liposomes of the presently described pegylated RGDK-lipopeptide exhibit synergism in inhibiting proliferation, invasion and migration of both tumor and endothelial cells presumably by inhibiting proliferation and metastasis related genes both at mRNA & protein levels. Pronounced tumor growth inhibition was observed in mice treated with formulations containing both the drugs. Tumor growth inhibition was found to be 2-3 folds less in mice treated with formulations containing only curcumin or only doxorubicin. The presently described liposomal system is expected to find future use for simultaneously delivering potentially any combinations of hydrophilic and hydrophobic potent small molecule cancer therapeutics to tumor vasculature in anti-angiogenic cancer therapy.

Autophagy is one of the well-known pathways to accelerate the clearance of protein aggregates, which contributes to the therapy of neurodegenerative diseases. Although there are numerous reports that demonstrate the induction of autophagy with small molecules including rapamycin, trehalose and lithium, however, there are few reports mentioning the clearance of aggregate-prone proteins through autophagy induction by nanoparticles. In the present article, we have demonstrated that europium hydroxide [Eu(III)(OH)3] nanorods can reduce huntingtin protein aggregation (EGFP-tagged huntingtin protein with 74 polyQ repeats), responsible for neurodegenerative diseases. Again, we have found that these nanorods induce authentic autophagy flux in different cell lines (Neuro 2a, PC12 and HeLa cells) through the expression of higher levels of characteristic autophagy marker protein LC3-II and degradation of selective autophagy substrate/cargo receptor p62/SQSTM1. Furthermore, depression of protein aggregation clearance through the autophagy blockade has also been observed by using specific inhibitors (wortmannin and chloroquine), indicating that autophagy is involved in the degradation of huntingtin protein aggregation. Since [Eu(III)(OH)3] nanorods can enhance the degradation of huntingtin protein aggregation via autophagy induction, we strongly believe that these nanorods would be useful for the development of therapeutic treatment strategies for various neurodegenerative diseases in near future using nanomedicine approach.

Ever since the finding that αvβ3 integrin receptors are over expressed on the endothelial cell surfaces of tumor vasculatures relative to normal resting vasculatures was disclosed in 1994, αvβ3 integrin receptor selective systems are finding increasing applications both for targeting anti-cancer drugs/genes selectively to tumor vasculatures and for imaging growing tumors. Among the cyclic peptide based integrin antagonists identified through both phage display and structure-activity studies, mainly αvβ3 integrin selective cyclic peptide c(RGDfK-) has found most widespread exploitations for targeting chemotherapeutic drugs/genes to both tumor and tumor vasculatures in anti-angiogenic cancer therapy. Herein we show that a lipopeptide containing widely acclaimed αvβ3 integrin receptor selective cyclic RGDfK ligand in its head-group area can effectively deliver genes into both the endothelial and tumor cells via all the three widely used integrin receptors namely αvβ3, αvβ5 & α5β1 integrins. We demonstrate that intravenous administration of the electrostatic complex of the cationic liposomes of an amphiphiles with cyclic RGDfK head-group and the anti-cancer p53 gene leads to significant tumor growth inhibition in a syngeneic mouse tumor model presumably through inducing apoptosis of tumor neovasculatures. The findings delineated herein provide experimental evidence that cyclic-RGDfK-ligand may not be that highly selective for αvβ3 integrin receptor as is popularly believed.