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A Microdevice for Platelet-Rich Plasma (PRP) Separation from Blood

Name: Vijai Laxmi

Name of supervisor: Prof. Amit Agrawal and Prof. Suhas S Joshi

Department: Mechanical Engineering

 

Topic of research: A Microdevice for Platelet Rich Plasma Separation from Blood
Description of research work:
A Microdevice for Platelet-Rich Plasma (PRP) Separation from Blood

Importance or applications of the research

The aim of our work is to develop a microdevice for platelet-rich plasma (PRP) separation. Platelets are subcellular fragments of size 2-3 µm in diameter and 0.5 µm thick in the shape of discs originated from the megakaryocytes. They circulate in human blood vessels in resting form near the apical surface of the endothelium to provide a quick response to vascular damage. In addition, platelets are a treasure trove of several proteins, enzymes, and platelet derived growth factors (PDGF). These PDGFs and proteins accelerate soft tissue healing and bone regeneration. Platelet rich plasma is a suspension of large number of platelets, approximately 3-8 times higher than the normal physiological level (1.5 - 4.5 x105/µl) in blood plasma. The presence of platelets above the normal level concentrates these proteins and growth factors in a small volume of plasma, which enhances the healing and rejuvenation processes. Therefore, platelet-rich plasma or platelet concentrate may be used for tissue regeneration, wound healing, skin rejuvenation, sports medicine, and in dermatology. Separated platelets can also be used in transfusion for patients undergoing treatment for dengue, dental surgery, and chemotherapy etc. 

Novelty

The developed microdevice is a passive device as opposed to the active devices that are mostly reported in literature. It does not need a sheath flow thereby reducing the number of accessories required for its operation. It employs relatively large dimensions so that it is easy to fabricate. The microdevice yields a high amount of platelet enrichment (beyond the requirement of 3-8 times with respect to the physiological level) and exhibits a clog-free operation, making it a reliable device in practical setting. The platelets obtained from the microdevice have been biologically characterized; the platelets are not activated and no change in their pH or morphology is noted; which is better than the conventional way of their separation through a centrifuge. The development of this microdevice, therefore marks a significant contribution.  As to the best of our knowledge, this is the first attempt to utilize platelet transport mechanisms in microflows to extract and enrich platelets in the plasma. 

Methodologies adopted

The microdevice was designed considering combined effect of biophysical laws, geometrical effects, and hydrodynamic forces for its functioning. Microdevice was fabricated using conventional softlithography and photolithography process. All the fabrication processes were carried out in house using micro fabrication facility at Center for Excellence in Nanotechnology (CEN) and Microfluidics lab, at IIT Bombay. Experiments were performed with whole blood samples. Samples obtained from the microdevice were analysed using Flow cytometer and Hemocytometer. 

Most significant results

Our microdevice is able to achieve 14.55+1.81 (n=3) fold platelets enrichment in the plasma. Several biological tests such as activation level, morphology test, pH level shows that there is no significant effect of microdevice separation process on the obtained platelets. A comparison of the microdevice with available microdevices shows the superior performance of the present microdevice, and suggests that passive microdevices can attain or even surpass the performance of active microdevices. 

Conclusions

The developed microdevice is compact (3 cm×2 cm ×0.5 cm in size), easy to fabricate, requires less hardware and pumping power than available microdevices, and separates high quality platelets from whole blood sample. The microdevice is able to enrich platelets to 14.55+1.81(n=3) folds in the plasma while working with the whole blood sample. The high dimensions of microchannel (60 µm – 350 µm) and absence of the microstructures (pillars/obstacle) in the microchannel provide clog-free separation from the microdevice. A range of biological tests were performed on the separated PRP sample to check quality of the platelets post separation. The activation level, morphology test or pH level did not show any significant change after separating from the microdevice, which confirms the high quality of the platelets obtained from the microdevice. The developed microdevice is expected to be employed on field for treatment of sports injury, and in dermatology applications. While several of these microdevices operating in parallel can be employed for extracting platelets selectively from the donor’s blood for transfusion purposes for the treatment of dengue, and surgeries .

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Figure: Schematic of developed microdevice for platelet-rich plasma separation from whole blood.