TPGS-Modified Long-Circulating Liposomes Loading Ziyuglycoside I for Enhanced Therapy of Myelosuppression

BACKGROUND: Ziyuglycoside I (ZgI), an active ingredient isolated from traditional Chinese medicine Sanguisorba officinalis L, has been demonstrated to increase the leucocytes and protect hematopoietic stem cells. However, the poor solubility and a short half-life of ZgI limit its bioavailability and efficacy. The D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) has been widely used to increase the solubility, improve the encapsulation rate, and extend the half-life of drugs. METHODS: Here, we formulated the TPGS-modified long-circulating liposomes loading ZgI with a sustained drug release and enhanced therapy for myelosuppression. ZgI-TPGS-liposomes were manufactured using a thin-film hydration technique, followed by characterizations of physicochemical properties, including the particle size, zeta potential, TEM, SEM, FTIR, XRD, stability, drug loading (DL), encapsulation efficiency (EE). The in vitro and in vivo delivery efficiency were further evaluated by cellular uptake, in vitro drug release and in vivo pharmacokinetics. Finally, therapeutic effect on myelosuppression was investigated. RESULTS: The ZgI-TPGS-liposomes had an particle size of 97.89 ± 1.42 nm and ZP of −28.65 ± 0.16 mV. It exhibited DL of 9.06 ± 0.76% and EE of 92.34 ± 3.83%, along with excellent storage stability, cellular uptake and sustained drug release to free ZgI and liposomes without TPGS. Additionally, the TPGS modified liposomes significantly enhanced the therapeutic effect of ZgI on CTX induced myelosuppression, which can be confirmed in the apoptosis inhibition and cell viability promotion of CTX injured HSPC-1 cells. Also, the mice in vivo pharmacodynamics demonstrated that TPGS liposomes promoted ZgI increasing the numbers of leucocytes and neutrophils in myelosuppression mice induced by CTX. CONCLUSION: Our research suggest that TPGS-modified long-circulating liposomes loading ziyuglycoside I has potential application in myelosuppression therapy.