Martin E. Kolewe

Bio: Martin E. Kolewe is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Cell aggregation & Tissue engineering. The author has an hindex of 11, co-authored 19 publications receiving 652 citations. Previous affiliations of Martin E. Kolewe include University of Massachusetts Amherst.

Pharmaceutically Active Natural Product Synthesis and Supply via Plant Cell Culture Technology

Abstract: The chemical diversity of plant-derived natural products allows them to function in a multitude of ways including flavor enhancers, agricultural chemicals, and importantly, human medicinals Supply of pharmaceutically active natural products is often a challenge due to the slow growing nature of some species, low yields found in nature, and unpredictable variability in accumulation Several production options are available including natural harvestation, total chemical synthesis, semisynthesis from isolated precursors, and expression of plant pathways in microbial systems However, for some medicinal natural products, such as the anticancer agent paclitaxel, where low yields in nature, chemical complexity and lack of knowledge of the complete biosynthetic pathway, preclude many of these options, plant cell culture technology is an attractive alternative for supply Plant cell suspension cultures are amenable to scale-up, environmental optimization, and metabolic engineering This review focuses on some of the key challenges in utilizing and commercializing plant cell culture suspension technology, with a focus on pharmaceutically active natural products Recent research has been directed toward application of traditional strategies such as reactor design, cell immobilization, and enzyme elicitation as well as emerging strategies such as characterizing cellular heterogeneity and variability through flow cytometric techniques, metabolic engineering, and system-wide analysis

3D Structural Patterns in Scalable, Elastomeric Scaffolds Guide Engineered Tissue Architecture

Abstract: Microfabricated elastomeric scaffolds with 3D structural patterns are created by semiautomated layer-by-layer assembly of planar polymer sheets with through-pores. The mesoscale interconnected pore architectures governed by the relative alignment of layers are shown to direct cell and muscle-like fiber orientation in both skeletal and cardiac muscle, enabling scale up of tissue constructs towards clinically relevant dimensions.

Characterization of aggregate size in Taxus suspension cell culture.

Abstract: Plant cells grow as aggregates in suspension culture, but little is known about the dynamics of aggregation, and no routine methodology exists to measure aggregate size. In this study, we evaluate several different methods to characterize aggregate size in Taxus suspension cultures, in which aggregate diameters range from 50 to 2,000 μm, including filtration and image analysis, and develop a novel method using a specially equipped Coulter counter system. We demonstrate the suitability of this technology to measure plant cell culture aggregates, and show that it can be reliably used to measure total biomass accumulation compared to standard methods such as dry weight. Furthermore, we demonstrate that all three methods can be used to measure an aggregate size distribution, but that the Coulter counter is more reliable and much faster, and also provides far better resolution. While absolute measurements of aggregate size differ based on the three evaluation techniques, we show that linear correlations are sufficient to account for these differences (R 2 > 0.99). We then demonstrate the utility of the novel Coulter counter methodology by monitoring the dynamics of a batch process and find that the mean aggregate size increases by 55% during the exponential growth phase, but decreases during stationary phase. The results indicate that the Coulter counter method can be routinely used for advanced process characterization, particularly to study the relationship between aggregate size and secondary metabolite production, as well as a source of reliable experimental data for modeling aggregation dynamics in plant cell culture.

Biodegradable scaffold with built-in vasculature for organ-on-a-chip engineering and direct surgical anastomosis

Abstract: We report the fabrication of a scaffold (hereafter referred to as AngioChip) that supports the assembly of parenchymal cells on a mechanically tunable matrix surrounding a perfusable, branched, three-dimensional microchannel network coated with endothelial cells. The design of AngioChip decouples the material choices for the engineered vessel network and for cell seeding in the parenchyma, enabling extensive remodelling while maintaining an open-vessel lumen. The incorporation of nanopores and micro-holes in the vessel walls enhances permeability, and permits intercellular crosstalk and extravasation of monocytes and endothelial cells on biomolecular stimulation. We also show that vascularized hepatic tissues and cardiac tissues engineered by using AngioChips process clinically relevant drugs delivered through the vasculature, and that millimetre-thick cardiac tissues can be engineered in a scalable manner. Moreover, we demonstrate that AngioChip cardiac tissues implanted with direct surgical anastomosis to the femoral vessels of rat hindlimbs establish immediate blood perfusion.

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications

Abstract: Surface modification and endothelialization of vascular biomaterials are common approaches that are used to both resist the nonspecific adhesion of proteins and improve the hemocompatibility and long-term patency of artificial vascular grafts. Surface modification of vascular grafts using hydrophilic poly(ethylene glycol), zwitterionic polymers, heparin or other bioactive molecules can efficiently enhance hemocompatibility, and consequently prevent thrombosis on artificial vascular grafts. However, these modified surfaces may be excessively hydrophilic, which limits initial vascular endothelial cell adhesion and formation of a confluent endothelial lining. Therefore, the improvement of endothelialization on these grafts by chemical modification with specific peptides and genes is now arousing more and more interest. Several active peptides, such as RGD, CAG, REDV and YIGSR, can be specifically recognized by endothelial cells. Consequently, graft surfaces that are modified by these peptides can exhibit targeting selectivity for the adhesion of endothelial cells, and genes can be delivered by targeting carriers to specific tissues to enhance the promotion and regeneration of blood vessels. These methods could effectively accelerate selective endothelial cell recruitment and functional endothelialization. In this review, recent developments in the surface modification and endothelialization of biomaterials in vascular tissue engineering are summarized. Both gene engineering and targeting ligand immobilization are promising methods to improve the clinical outcome of artificial vascular grafts.

Marine natural products: a new wave of drugs?

Abstract: The largely unexplored marine world that presumably harbors the most biodiversity may be the vastest resource to discover novel ‘validated’ structures with novel modes of action that cover biologically relevant chemical space. Several challenges, including the supply problem and target identification, need to be met for successful drug development of these often complex molecules; however, approaches are available to overcome the hurdles. Advances in technologies such as sampling strategies, nanoscale NMR for structure determination, total chemical synthesis, fermentation and biotechnology are all crucial to the success of marine natural products as drug leads. We illustrate the high degree of innovation in the field of marine natural products, which in our view will lead to a new wave of drugs that flow into the market and pharmacies in the future.