Resumen de Nanotechnological strategies for coating and encapsulation of therapeutic proteins
Nanotechnology is considered one of the key technologies of the 21st century. At the meeting point of many different areas such as physics, chemistry, biology, medicine and electronics, nanotechnological applications in the field of natural sciences are of special interest. Nanomedicine in particular, explores the potential of a huge variety of nanomaterials in medicine, covering both disease diagnosis and treatment. Prominent fields in nanomedicine include drug delivery, cell and gene therapy, molecular diagnostics and imaging.
Regarding disease treatment and drug delivery, protein-based therapeutics have had an important impact in a myriad of human disease for the last decades. Many drugs of peptide and protein nature such as enzymes and antibodies have been approved and become effective therapies for diseases like diabetes, cancer and Lysosomal Storage Diseases (LSD). Protein therapeutics offer significant advantages over conventional drugs including higher specificity, greater activity and lower toxicity. However, limitations in the use of therapeutic proteins, such as sensitivity to enzymatic degradation,short circulation half-lives in the bloodstream and poor membrane permeability; severely affect protein efficiency, stability and at the end, their therapeutic capacity.
The use of nanotechnologial strategies, such as protein encapsulation and chemical modification of proteins, offer promising expectations to overcome the limitations of protein therapies and improve their therapeutic efficacy.
In this thesis, it has been studied the application of several nanotechnological strategies for protein encapsulation and coating in order to improve the therapeutic value of those proteins. Two proteins were focused, both with therapeutic value in disease treatment, but because of their differences regarding size, structural complexity and enzymatic activity, strategies on each of them need to be addressed particularly.
Epidermal Growth Factor is a 6 kDa protein with mitogenic activity that has been described in many studies to have an important role in the healing of diseases like peptic ulcers. EGF can increase the healing rate of sores in lining of the stomach and the duodenum. However, the harmful environment for proteins found in the gastrointestinal lumen, with extreme pH and the presence of proteases, may induce EGF degradation and a subsequent loss of its biological activity. We suggest a strategy for EGF co-encapsulation in PLGA nanoparticles with NvCI, a digestive carboxypeptidase inhibitor, in order to protect it from protease degradation and thus increasing its therapeutic capacity. EGF and NvCI can be successfully encapsulated in PLGA nanoparticles, maintaining its biological activity.
Velaglucerase alfa is a recombinant version of the human -glucocerebrosidase (GBA), a protein drug used in Enzyme Replacement Therapy (ERT) for Gaucher Disease (GD), a Lysosomal Storage Disorder (LSD). LSD are diseases that present a defective lysosomal enzyme, GBA in the case of GD, causing accumulation of their substrate and impairing the normal function of lysosomes. ERT consists in administrating a functional version of the defective enzyme intending its delivery into the lysosome to restore the enzymatic activity. Velaglucerase is a 63 kDa protein with intrinsic enzymatic activity, and because of its structural complexity encapsulation in PLGA nanoparticles is unable to preserve enzymatic activity. Polymer Masked-Unmasked Protein Therapy (PUMPT) is a strategy that consists in conjugating a protein with a biodegradable polymer. Conjugation of Velaglucerase with the biocompatible polymer Poly(L-Glutacic acid) is able to mask and preserve the enzyme activity of Velaglucerase until its delivery into the lysosome, where it partially restores the GBA activity levels. PGA conjugation also grants Velaglucerase a higher stability in human blood plasma.
Developing new nanotechnological methods capable of encapsulating or coating large proteins whose biological activity is sensitive to environmental conditions offers promising expectations in order to improve their therapeutic capacity.
