Polyhemoglobin-tyrosinase and artificial cells microencapsulated tyrosinase for the removal of systemic tyrosine : a potential novel therapy for melanoma
Year: 2002
Type: dissertation
Abstract: Artificial cells microencapsulation have a number of potential areas of application. Studies showed that lowering of tyrosine level could inhibit the growth of melanoma. However, at present there is no practical method to lower the tyrosine level in humans. We have therefore devised novel methods as follows. (1) Microencapsulation of tyrosinase for the removal of systemic tyrosine by oral administration. Characterization, optimization, and feasibility studies were carried out to test the therapeutic potentials. In temperature and pH studies, the encapsulated tyrosinase maintained higher enzyme activity than the free enzyme in solution. The in vivo studies showed that daily oral administration of encapsulated tyrosinase by itself for about 3--5 days could lower the body tyrosine level. (2) A novel polyhemoglobin-tyrosinase preparation for intravenous injection can rapidly lower the body tyrosine level after one intravenous injection. In this form, the enzyme is covered by hemoglobin molecules and therefore has less immunological properties. Furthermore, polyhemoglobin is an oxygen carrier and being in a solution, it can more readily reach the narrower capillaries of the melanoma cancer cells than red blood cells and can therefore bring more oxygen for radiation therapy. Our in vitro studies showed that this novel polyhemoglobin-tyrosinase preparation inhibited the growth of melanoma cells in culture. (3) A combination of two intravenous injections of polyhemoglobin-tyrosinase with 3 times a day oral administration of encapsulated tyrosinase could immediately lower the body tyrosine and maintained this low level as long as the oral administration was continued.
Source: eScholarship@McGill (McGill)
DOI: 10.82308/8371
Author: Binglan Yu
Language: English
Subfield: Biotechnology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7014643137