Safflower injected as prophylaxis for RVO in rabbits


Image credit: AdobeStock/Vera Kuttelvaserova

(Image credit: AdobeStock/Vera Kuttelvaserova)

An experimental rabbit study of the effects of safflower injections found that the injections had a positive effects in the short term in the rabbits with retinal vein occlusion (RVO). Within a short period, the retinal blood flow was significantly higher in the RVO group and retinal vein thrombosis was delayed,1 according to researchers from the Department of Ophthalmology, Tianjin Beichen Hospital, Affiliated Hospital of Nankai University, No. 7, Tianjin, China.

RVO is a significant chronic retinal vascular disorder and the second most common cause of vision impairment after diabetic retinopathy. Affected patients can experience a devastating loss of vision within 3 years of development of RVO.2

The current treatments, i.e., fundus laser photocoagulation, corticosteroid therapy, and anti-vascular endothelial growth factor injections, offer some therapeutic benefits, but they are less than ideal in safety and efficacy.

The investigators explained that safflower injection, primarily comprised of safflower yellow (SY), carthamone, carthamidin, and neocarthamin, can prevent thrombosis. “SY, the main active component, inhibits thrombosis by blocking adenosine 5'-diphosphate receptors, reducing thromboxane A2 synthesis, enhancing prostacyclin production, and diminishing the activity of plasma plasminogen activator inhibitor,”3 they explained.

Rabbit study

In light of the fact that there is widespread clinical application of SY and knowledge of its diverse pharmacologic effects, little research has been carried out on its ability to prevent retinal vein thrombosis. The goal of the current study was to assess the effect and mechanism of safflower injections in preventing retinal vein thrombosis in 20 healthy adult pigmented rabbits.

The rabbits divided randomly between the experimental group treated with safflower injection and the control group given normal saline. Blood samples were collected 2 weeks after treatment to analyze platelet adhesion and aggregation rates. Photodynamic therapy was used to induce occlusion in the target retinal vein.

The authors reported, “The experimental group exhibited significantly lower rates of platelet adhesion and aggregation compared to the control group. Following induction of RVO, the experimental group showed a lower complete occlusion rate of the target retinal vein.”

The effect of the safflower injections seemed to occur rapidly. While the investigators found that the initial blood flow in the target vein was similar in the 2 groups, the blood flow at 1, 3, and 5 minutes after occlusion was significantly higher in the experimental group.

“The safflower injection delayed retinal vein thrombosis formation, preserved blood flow in the affected retinal area, and reduced platelet adhesion and aggregation. These effects facilitated vascular reperfusion within a limited timeframe,” the authors stated.

They explained further that safflower injection, which is based on traditional Chinese medicine, prevents thrombosis by inhibiting platelet adhesion and aggregation. It helps to maintain blood flow in the vessels that could otherwise be compromised by RVO.

Considering their results, the research team suggests that comprehensive clinical trials with a prospective design, involving multiple centers, and a large sample of human participants, are warranted to verify the effectiveness of safflower injection in reducing the incidence and severity of RVO and its associated complications in humans.

1. Li J, Guo Z, Wu J. Investigation into safflower injection as a prophylactic treatment for retinal vein occlusion in a rabbit model. Sci Rep. 2024;14:8048;
2. Rogers SL, McIntosh RL, Lim L, et al. Natural history of branch retinal vein occlusion: an evidence-based systematic review. Ophthalmology. 2010;117:1094–1101; doi: 10.1016/j.ophtha.2010.01.058
3. Lu PH, Kuo C-Y, Chan C-C, et al. Safflower extract inhibits ADP-induced human platelet aggregation. Plants (Basel). 2021;10:1192.

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