Gene Therapy

Our main research interest is the development of therapeutic strategies for retinal pathologies.

For this, we employ gene therapy strategies based on non-viral vectors for diseases such as diabetic retinopathy, retinopathy of prematurity, Lebers’ Congenital Amaurosis and Retinitis Pigmentosa.

For this purpose, our approach is four-fold:

  • Develop non-viral vectors based on natural and synthetic polymers such as chitosan, hyaluronic acid, and PDMAEMA.
  • Optimize of the delivery and expression of genes of interest, using more efficient plasmid-based expression systems and linkage of nuclear localization signals.
  • Contribute to the definition of the ethiology and identification of new therapeutic approaches for treating retinal diseases, with emphasis on RAS (Renin Angiotensin-System), PEDF and anti-angiogenic VEGF isoforms.
  • Use combinatorial approaches to efficiency target specific retinal cells.
  • PTDC/CTM/REF/2679/2020 – SmartGlauco - Smart Drug Delivery Device for Glaucoma Treatment. Investigador (Principal Investigator at NMS). Fundação para a Ciência e Tecnologia (FCT), Portugal. 2021-2023.

  • PTDC/BTM-ORG/0500/2021: RBPing: Exploring the therapeutic potential of RBP3 in retinal gene therapy. Principal Investigator. January 2022-December 2023. 

  • PTDC/BTM-ORG/28121/2017. TARGET - TArgeting diabetic Retinopathy with GEne Therapy. Role: Principal Investigator. 2018-2021. Funded by the Foundation for Science and Technology (FCT), Portugal and Lisbon Regional Operational Programme.
    Our long-term goal is the development of gene therapy-based therapies for diabetic retinopathy. We hypothesize that growth factor imbalance plays a critical role in diabetic retinopathy and restoring balance by inhibiting angiogenic factors and expression of anti-angiogenic factors may improve RD. In a first approach, we evaluated the levels of factors of interest in diabetic and non-diabetic vitreous humor to determine their relevance. Gene therapy with plasmids and optimized non-viral vectors promotes the inhibition of PlGF and expression of PEDF and VEGF165b. The in vitro efficiency will be tested in RPE cells, which are the source of trophic factors in the retina, and in vivo in a mouse model of DR, through histological evaluation and retinal function by visual tests.
    In this last year of execution, this project already has 4 publications, 1 doctoral and 3 master's thesis, as well as 14 communications at conferences.

  • INOVA4HEALTH project - SynDia - Investigating the role of synucleins in diabetic retinopathy. Principal investigator. 2016-2018.
    The hypothesis underlying this project is that synuclein members play a common pathological role in retinopathies in both Parkinson's disease (PD) and diabetes. The specific objectives of this project were: 1) To establish a correlation between the expression profile of synuclein and the progression of retinopathy in the developmental stages of diabetes and PD in animal models of both diseases; 2) Test the presence of synucleins in the ocular fluids of diabetic patients and assess their correlation with disease severity; 3) Design therapeutic approaches for the treatment of retinal dysfunction in diabetic retinopathy and PD.

  • EXPL/BIM-MEC/1433/2013 - “Targeting the renin-angiotensin system for the treatment of retinal diseases“. Principal investigator. Funded by the Foundation for Science and Technology (FCT), Portugal. January 2014-March 2015.
    This project aimed to assess the therapeutic potential of targeting the RAS system which has recently been described in the eye as potentially implicated in pathological conditions such as diabetic retinopathy. It also intended to explore the potential of aliskiren, a drug used in situations where the RAS system is involved, as a therapy for diabetic retinopathy.This project resulted in 3 publications in international peer-reviewed journals, 4 communications at conferences.

  • PIRG05-GA-2009-249314 - Marie Curie Reintegration Grant. "EyeSee - Development of new gene therapy approaches for the treatment of ocular neovascularization", Principal Investigator. 2009-2013. Funded by the European Commission under the FP7 programme.
    This project resulted in 15 publications in international peer-reviewed journals, 23 communications at conferences, 3 doctoral theses and 5 masters theses. The results obtained allowed us to obtain new therapeutic strategies that will be tested in different animal models of retinal pathologies.

  • PTDC/SAU-BEB/098475/2008 - "Development of non-viral vectors for ocular gene therapy". 2010-2013. Foundation for Science and Technology (FCT), Portugal.
    The results obtained allowed us to obtain a set of non-viral vectors for ocular gene therapy for testing in different animal models of retinal pathologies. This project resulted in 10 publications in international peer-reviewed journals, 20 communications at conferences, 3 doctoral theses and 5 masters theses.


  • S. M. Calado, A. V. Oliveira, S. Machado, A. P. Silva, R. Haase, G. A. Silva, Sustained gene expression in the retina by improved episomal vectors. Tissue Engineering: Part A 20:19-20. pp 2692-2698. 2014. DOI:10.1089/ten.TEA.2013.0672
  • A. V. Oliveira, G. A. Silva*, D. C. Chung. Enhacement of chitosan-mediated gene delivery through combination with phiC31 integrase. Acta Biomaterialia 17:89-97. 2015. DOI: 10.1016/j.actbio.2015.01.013. *Corresponding Author.
  • A.V. Oliveira, A. Marcelo, A.M. Rosa da Costa, G.A. Silva. Ev aluation of cystamine-modified hyaluronic acid/chitosan polyplex as a retinal gene vector. Material Science and Engineering C, 58:264-72. 2016. DOI: 10.1016/j.msec.2015.08.047. 
  • S.M. Calado, F. Diaz-Corrales, G.A. Silva. pEPito-driven PEDF expression ameliorates Diabetic Retinopathy hallmarks. Human Gene Therapy: Methods. Volume: 27 Issue 2.
  • S. Simão, D.B. Bitoque, S.M. Calado, G.A. Silva. Oxidative stress modulates the expression of VEGF isoforms in the diabetic retina. 2016. New Frontiers in Ophthalmology. 2(2):77-83. doi: 10.15761/NFO.1000119.
  • S.M. Calado, L. Alves, S. Simão, G.A. Silva. GLUT1 activity contributes to the impairment of PEDF secretion by the RPE. Molecular Vision 2016 22:761-770. 
  • S. Simão, D.F. Santos, G.A. Silva. Aliskiren inhibits the renin-angiotensin system in retinal pigment epithelial cells. European Journal of Pharmaceutical Sciences 2016 92:22-7. doi:10.1016/j.ejps.2016.06.019.  
  • D. M. Bitoque, S. Simao, A. V. Oliveira, S. Machado, E. Lopes, M. R. Duran, A. M. R. Costa, G. A. Silva. Efficiency of RAFT-synthesized PDMAEMA in gene transfer to the retina. Journal of Tissue Engineering and Regenerative Medicine. 2017.
  • S. Simão, D.F. Santos, G.A. Silva. Aliskiren Decreases Oxidative Stress and Angiogenic Markers in Retinal Pigment Epithelium Cells. Angiogenesis. 2017 Feb;20(1):175-181. Doi:10.1007/s10456-016-9526-5.
  • A.V. Oliveira, A.M. Rosa da Costa, G.A. Silva. Non-viral gene strategies for ocular gene delivery. Materials Science and Engineering C. 2017.
  • R.S. Araújo, D.F. Santos, G.A.Silva. The role of the retinal pigment epithelium and Müller cells secretome in neovascular retinal pathologies. Biochimie. 2018.
  • D.B. Bitoque, G.A. Silva. Molecular biology tools for the study and therapy of PDE6beta mutations. Journal of Biotechnology, 284, pp 1-5.
  • D.B. Bitoque, A.M Rosa da Costa, G.A. Silva. Insights on the intracellular trafficking of PDMAEMA gene therapy vectors. Materials Science and Engineering C, 93, pp 277-288.
  • F. Carvalho, S.M. Calado, G.A. Silva, G.S. Diogo, J. Moreira-Silva, R.L. Reis, L. Cancela, P.J. Gavaia. Altered bone microarchitecture in a type 1 diabetes mouse model Ins2Akita. Journal of Cellular Physiology, 234(6), pp 9338-9350.
  • M. Machado, G.A. Silva, D.B. Bitoque, J. Ferreira, L.A. Pinto, J. Morgado, Q. Ferreira. Self-assembled multilayer films for time-controlled ocular drug delivery. ACS Applied Bio Materials.
  • F. Pires, J. Santos, D.B. Bitoque, G.A. Silva, A. Marletta, V. Nunes, P. Ribeiro, J. Silva, M. Raposo. Polycaprolactone/gelatin nanofiber membranes containing EGCG loaded liposomes and their potential use for skin regeneration. ACS Applied Bio Materials.
  • R.S Araújo, M.S. Silva, D.F. Santos, G.A. Silva. Dysregulation of trophic factors contributes to diabetic retinopathy in the Ins2Akita mouse. Experimental Eye Research. Vol 194. May 2020, 108027.
  • R.S. Araújo, G.A. Silva. PlGF silencing combined with PEDF overexpression: modeling RPE secretion as potential therapy for retinal neovascularization. Molecular Biology Reports. 47, 4413-4425.
  • R.S. Araújo, D.B. Bitoque, G.A. Silva. Dual-acting antiangiogenic gene therapy reduces inflammation and regresses neovascularization in diabetic mouse retina. Molecular Therapy. 2020; 22:329.339. doi: 10.1016/j.omtn.2020.08.036.


  • D.B. Bitoque*, J. Morais*, A.V. Oliveira*, S. Simão, T.M. Fortunato, S.M. Calado, R. Sequeira, A.M Rosa da Costa, G.A. Silva. Human-derived NLS enhance nonviral transfection. Bioscience Reports. 2021. 41(1). doi:10.1042/BSR20201026. *Equal contribution. 
  • R.S. Araújo, D.B. Bitoque, G.A. Silva. Development of Strategies to Modulate Gene Expression of Angiogenesis-related Molecules in the Retina. Gene 791, 145724.
  • A.C. Almeida, G.A Silva, G. Santini, M. Brízido, M. Correia, C. Coelho, L.M Borrego. Hyperglycemia is linked to Retinopathy of Prematurity. Scientific Reports 11(1), 22321. 
  • A.C. Almeida, D.B. Bitoque, M. Brízido, C. Martins, C. Coelho, L.M Borrego, G.A Silva. Serum levels of Placental Growth Factor reflect the severity of Retinopathy of Prematurity. Acta Paediatrica 110(10), 2778. 
  • D.S.M. Pereira, A.M. Pereira, T.C. Castanho, G.A. Silva, F. Falcão, P. Costa, J.M. Pêgo. Applicability and Validation of the Reaction to Tests Scale (RTT) in a sample of Portuguese medical students. BMC Psychology 9, 1, 166. 
  • D.F. Santos, M. Pais, C.S. Santos, G.A. Silva. Polyphenol metabolite pyrogallol-O-sulfate decreases microglial activation and pro-angiogenic VEGF in retinal pigment epithelium cells and diabetic mouse retina. International Journal of Molecular Sciences. Special issue on Retinal Neurodegenerative Diseases: Molecular targets driving neuroinflammation and neuroprotection. 22(21), p11402.   


  • A.M.L. Oliveira, M. Machado, G.A. Silva, D.B. Bitoque, J. Ferreira, L.A. Pinto, Q. Ferreira. Graphene Oxide Thin Films with Drug Delivery Function. Nanomaterials 2022, 12(7), 1149. doi: 10.3390/nano12071149
  • D.B. Bitoque*, C. Fernandes*, A.M.L. Oliveira, G.A. Silva. Strategies to improve the  targeting of retinal cells by gene therapy vectors . Frontiers in Drug Delivery. *Equally contributing authors. doi: 10.3389/fddev.2022.899260.
  • M. Machado, A.M.L. Oliveira, G.A. Silva, D.B. Bitoque, J. Ferreira, L.A. Pinto, Q. Ferreira. Graphene biosensors - a molecular approach. Nanomaterials 2022, 12(10), 1624. doi: 10.3390/nano12101624.
  • S. Talebin, B. Mendes, J. Conniot, D.B. Bitoque, G.A.Silva, J. Conde, G.G. Wallace. Biopolymeric coatings for local release of therapeutics from biomedical implants. Advanced Science.
  • 2015
    Travel Award for best podium communications, attributed to communication: S.M. Calado, L. Alves, G.A. Silva. Hyperglycemia and hypoxia induce overexpression of GLUT1 in models of Diabetic Retinopathy. EASD 2015 Annual Meeting, Stockholm, September 2015.

  • 2016
    Janssen Innovation Award 2016: Honorable mention for the work “Aliskeren as a new therapeutic approach for the treatment of diabetic retinopathy”.

  • 2018
    Best Poster Award, attributed to communication: DF Santos, M. Pais, C.S. Santos, G.A. Silva. Can (poly)phenols metabolites ameliorate the outcome of Diabetic Retinopathy?. 2nd International Conference on Food Bioactives and Health, Portugal, 2018. Poster communication.

  • 2019
    Poster communication entitled: “Characterisation and modulation of the Renin-Angiotensin System: Towards a new therapy for Diabetic Retinopathy.”, by Brigite Cabrita, D.F. Santos, G.A. Silva, selected as a finalist in the iMed 11.0(R) Innovation competition.

  • 2020
    Distinction for best oral communication attributed to communication R. Araújo, G.A. Silva, Dual gene therapy approach for the treatment of diabetic retinopathy. National Meeting of the Portuguese Society of Diabetology. 2020.

    Dr. Almeida Ruas Award, Best clinical project. G.A. Silva, “Analysis of the systemic levels of angiogenic and anti-angiogenic factors in diabetic retinopathy”. Portuguese Society of Diabetology.
PhD and Post Doc Opportunities @ Gabriela Silva's Lab
NMS teachers selected for international training on best practices in Digital Education

Professors José Belo and Gabriela Silva were selected to participate in the staff training "e_Desk - Digital & Entrepreneurial Skills for European teachers", within the scope of the European project e-DESK.

NMS researcher honored at an exhibition dedicated to women scientists

The International Day of Women and Girls in Science was celebrated at the Oficinas de Criatividade Himalaya-Centro de Ciência Viva dos Arcos with the inauguration of the exhibition Mulheres Arcuenses com Ciência, among them Gabriela Silva, principal investigator of NMS.

  • Ana M. Costa, Department of Chemistry, University of Algarve, Portugal.
    Collaboration in research projects for the development of non-viral vectors for retinal gene therapy. This collaboration resulted in 6 publications in international peer-reviewed journals, 8 communications at conferences.
  • Leonor Cancela, Department of Biomedical Sciences and Medicine, University of Algarve, Portugal.
    Collaboration in a research project, namely in bone studies of diabetic animal models.
  • Francisco Corrales, CABIMER, Seville, Spain.
    Collaboration in the supervision of doctoral students. This collaboration resulted in a publication in an international peer-reviewed journal and two communications at conferences.
  • Cláudia Santos and Regina Almeida, CEDOC-NMS/UNL, Portugal.
    Collaboration in research work on the effect of small fruits in conditions of diabetic retinopathy.
  • Sandra Tenreiro, CEDOC- NMS/UNL, Portugal.
    Collaboration in research work on the role of synucleins in conditions of diabetic retinopathy. Principal Co-investigators on the Syndia project, funded by INOVA4HEALTH, 2016-2018
  • Maria Raposo e Paulo Ribeiro, FCT-UNL, Caparica, Portugal.
    Biocompatibility assessment of materials for dermatological and drug delivery applications.
  • Marco Medeiros, CHULC e APDP, Lisboa, Portugal.
    Collaboration in the analysis of tropic factors in plasma and vitreous of patients with Diabetic Retinopathy.
  • Joana Ferreira, Diogo Maleita and Nuno Coelho, CHULC, Lisboa, Portugal.
    Collaboration in the analysis of tropic factors in the plasma of patients with Macular Edema.
  • Quirina Ferreira, IT, IST, U. Lisboa, Portugal.
    Evaluation of in vivo biocompatibility and functionality of materials for ocular drug delivery applications.
  • Ana Coroadinha, iBET-UNL, Oeiras, Portugal.
    Collaboration to assess the potential of optimized viral vectors in animal models of retinal degeneration.
  • Ana Herdade, iMM, U. Lisboa, Portugal.
    Evaluation of retinal structure and function in animal models of diabetic retinopathy and new therapeutic approaches, in the form of collaboration for retinal vasculature analysis.
  • Cláudia Lobato Silva and Gabriel Monteiro, IST, U. Lisboa, Portugal.
    Collaboration to study the therapeutic potential of “mini-circle” plasmids.
  • Ana Catarina Almeida and Margarida Brízido, Hospital Beatriz Ângelo, Loures, Portugal.
    Collaboration in the analysis of tropic factors in the plasma of patients with Retinopathy of Prematurity. This collaboration resulted in two publications. Additionally, it allowed the establishment of a collaboration protocol with the Ophthalmology Service of the HBA for the collection of vitreous humor (discarded during surgical procedures) and blood from diabetic and non-diabetic patients for the analysis of trophic factors in plasma and vitreous.


Principal Investigator

Gabriela Araújo da Silva


Diogo Bitoque
Post-Doctoral Researcher
Alexandra Oliveira
PhD Student
Madalena Carvalho
PhD Student
Cláudia Fernandes
Research Fellow
Beatriz Vaz
MSc Student