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Baltimore Highlands, MD, United States

Jiang X.,Johns Hopkins University | Jiang X.,Translational Tissue Engineering Center | Christopherson G.T.,Johns Hopkins University | Mao H.-Q.,Johns Hopkins University | And 2 more authors.
Interface Focus | Year: 2011

Previous studies have shown that substrate surface chemistry and topography exhibit significant impact on haematopoietic progenitor cell adhesion, proliferation and differentiation. In the present study, the effect of surface amine density and structure of grafted polymer chains on the adhesion and expansion of haematopoietic progenitor cells was investigated. Cryopreserved human umbilical cord blood CD133 + cells were expanded in cytokine-supplemented medium on ethylenediamine (EDA)- or 2-aminoethyl methacrylate hydrochloride (AEMA)-grafted polyethersulphone (PES) nanofibre scaffolds for 10 days. Although the percentage of CD34 + cells among the expanded cells increased with the surface amine density, the maximum fold expansion of CD34 + cells was obtained at a moderate amine density of 20-80 nmol cm -2.When comparing nanofibre matrices with similar amine densities, but prepared with two different methods, cells cultured on the AEMA-grafted PES nanofibre matrix showed lower fold expansion in terms of total cell number (300+84 fold) and CD34{thorn} cell number (68+19-fold) in comparison with those cultured on EDA-grafted nanofibres (787+84-fold and 185+84-fold, respectively). These results indicate that the surface amine density and the conjugate structure are important determinants for the preservation of CD34 surface marker and expansion efficiency of CD34 + cells. © 2011 The Royal Society.


Tammia M.,Johns Hopkins University | Martin R.,Johns Hopkins University | Mao H.-Q.,Johns Hopkins University | Mao H.-Q.,Whitaker Biomedical Engineering Institute
Current Opinion in Biotechnology | Year: 2011

Limitations in current nerve regeneration techniques have stimulated the development of various approaches to mimic the extrinsic cues available in the natural nerve regeneration environment. Biomaterials approaches modulate the microenvironment of a regenerating nerve through tailored presentation of signaling molecules, creating physical and biochemical guidance cues to direct axonal regrowth across nerve lesion sites. Cell-based approaches center on increasing the neurotrophic support, adhesion guidance and myelination capacity of Schwann cells and other alternative cell types to enhance nerve regrowth and functional recovery. Recent advances in presenting directional guidance cues in nerve guidance conduits and improving the regenerative outcomes of cell delivery provide inspirations to engineering the next generation of nerve repair solutions. © 2011 Elsevier Ltd.


Khalifian S.,Johns Hopkins University | Sarhane K.A.,Johns Hopkins University | Tammia M.,Johns Hopkins University | Ibrahim Z.,Johns Hopkins University | And 6 more authors.
Archivum Immunologiae et Therapiae Experimentalis | Year: 2015

Reconstructive transplantation has become a viable option to restore form and function after devastating tissue loss. Functional recovery is a key determinant of overall success and critically depends on the quality and pace of nerve regeneration. Several molecular and cellbased therapies have been postulated and tested in preclinical animal models to enhance nerve regeneration. Schwann cells remain the mainstay of research focus providing neurotrophic support and signaling cues forregenerating axons. Alternative cell sources such as mesenchymal stem cells and adipose-derived stromal cells have also been tested in pre-clinical animal models and in clinical trials due to their relative ease of harvest, rapid expansion in vitro, minimal immunogenicity, and capacity to integrate and survive within host tissues, thereby overcoming many of the challenges faced by culturing of human Schwann cells and nerve allografting. Induced pluripotent stem cell-derived Schwann cells are of particular interest since they can provide abundant, patientspecific autologous Schwann cells. The majority of experimental evidence on cell-based therapies, however, has been generated using stem cell-seeded nerve guides that were developed to enhance nerve regeneration across ‘‘gaps’’ in neural repair. Although primary end-to-end repair is the preferred method of neurorrhaphy in reconstructive transplantation, mechanistic studies elucidating the principles of cell-based therapies from nerve guidance conduits will form the foundation of further research employing stem cells in end-to-end repair of donor and recipient nerves. This review presents key components of nerve regeneration in reconstructive transplantation and highlights the pre-clinical studies that utilize stem cells to enhance nerve regeneration. © L. Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw, Poland 2014.


Patil R.R.,Johns Hopkins University | Yu J.,Johns Hopkins University | Banerjee S.R.,Johns Hopkins University | Ren Y.,Johns Hopkins University | And 7 more authors.
Molecular Therapy | Year: 2011

Successful translation of nonviral gene delivery to therapeutic applications requires detailed understanding of in vivo trafficking of the vehicles. This report compares the pharmacokinetic and biodistribution profiles of polyethylene glycol-b-polyphosphoramidate (PEG-b-PPA)/DNA micellar nanoparticles after administration through intravenous infusion, intrabiliary infusion, and hydrodynamic injection using single photon emission computed tomography/computed tomography (SPECT/CT) imaging. Nanoparticles were labeled with 111 In using an optimized protocol to retain their favorable physicochemical properties. Quantitative imaging analysis revealed different in vivo trafficking kinetics for PEG-b-PPA/DNA nanoparticles after different routes of administration. The intrabiliary infusion resulted in the highest liver uptake of micelles compared with the other two routes. Analysis of intrabiliary infusion by the two-compartment pharmacokinetic modeling revealed efficient retention of micelles in the liver and minimal micelle leakage from the liver to the blood stream. This study demonstrates the utility of SPECT/CT as an effective noninvasive imaging modality for the characterization of nanoparticle trafficking in vivo and confirms that intrabiliary infusion is an effective route for liver-targeted delivery of DNA-containing nanoparticles. © 2011 The American Society of Gene & Cell Therapy.


Nyland J.F.,University of South Carolina | Jiang X.,Johns Hopkins University | Jiang X.,Whitaker Biomedical Engineering Institute | Mao H.Q.,Johns Hopkins University | Mao H.Q.,Whitaker Biomedical Engineering Institute
Current Molecular Medicine | Year: 2013

Malaria sexual stage and mosquito transmission-blocking vaccines (SSM-TBV) have recently gained prominence as a necessary tool for malaria eradication. SSM-TBVs are unique in that, with the exception of parasite gametocyte antigens, they primarily target parasite or mosquito midgut surface antigens expressed only inside the mosquito. As such, the primary perceived limitation of SSM-TBVs is that the absence of natural boosting following immunization will limit its efficacy, since the antigens are never presented to the human immune system. An ideal, safe SSM-TBV formulation must overcome this limitation. We provide a focused evaluation of relevant nano-/microparticle technologies that can be applied toward the development of leading SSM-TBV candidates, and data from a proof-of-concept study demonstrating that a single inoculation and controlled release of antigen in mice, can elicit long-lasting protective antibody titers. We conclude by identifying the remaining critical gaps in knowledge and opportunities for moving SSM-TBVs to the field. ©2013 Bentham Science Publishers.

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