## 4 Discussion  
This work demonstrates that large-scale 3-D scaffold can be fabricated using the SLS printing method. The limitation of struts thickness growth due to heat conduction of particles was overcome using PGA microparticles over the conventional method based on NaCl salt particles. The resultant scaffolds were characterized by a micro-CT scan and SEM imaging. The PGA porogen leaching gave rise to 78% porosity. The porosity of the scaffold is essential for the distribution of the culture medium or blood plasma to ensure mass transfer and diffusion. (2018). The process of leaching out PGA microparticles by dissolving in NaOH is an easy process and does not disrupt the 3-D branched flow channels.  
The fabricated PCL scaffolds were seeded with Hep G2 for the illustration of metabolic functions. The albumin production, glucose metabolism, and lactate production remained active under perfusion culture system for 10 days. However, when the HUVECs were allowed to endothelize the Hep G2-covered scaffold, the albumin production was reduced. This limitation needs optimization to circumvent the functioning of Hep G2 in the co-culture system under a flow culture environment in a macro scaffold. The layer of endothelial cells grown on Hep G2 was observed by live imaging. The confluency of HUVECs on Hep G2 is crucial for imparting hemocompatibility.  
Hemocompatibility is an important issue when it comes to the development of transplantable internal organs. Determining hemocompatibility of the scaffold is vital to rule out possible blood trauma that such material may cause (2018). The confluency of EC lining on Hep G2 plays an important role in the overall assessment of hemocompatibility (2016; 2018). Complete endothelial of the engineered scaffold is essential for the long-term survival of functional tissue after implantation to avoid thrombosis and fibrosis (2018). The current prototype enables plasma perfusion within the flow channels. We screened the antiplatelet  
Figure 6: Hemocompatibility assessment: (**a**) SEM images of scaffold deposited with platelets on the control (no cell), Hep G2-covered scaffold, and co-culture (Hep G2 + HUVEC) scaffold. Platelet deposition and aggregation are shown by yellow arrows (scale bar is 20 μm, magnification 1000\(\times\)); (**b**) The % of platelet adhesion ratio (% of PAR) of the Hep G2-covered scaffold and co-cultured scaffold normalized to the control. Each column represents mean \(\pm\) SD with \(n\) = 3 independent experiments, * \(p<0.05\), *** \(p<0.005\) versus control.  
adhesion behavior of the scaffold, which was covered with Hep G2 and compared with endothelized Hep G2. The results revealed that there were significant differences between Hep G2 and endothelized Hep G2-covered scaffolds. The adherence of platelets on the Hep G2 scaffolds was much higher when compared with the endothelized Hep G2 scaffolds when perfused with platelets rich plasma. The reduction in platelet adherence is an indicator for the functional efficacy of HUVEC co-cultured with the Hep G2 scaffold. The presence of HUVECs significantly reduced the thrombogenicity of the scaffold. However, a key challenge of hemocompatibility with endothelized scaffolds holds potential in future application for tissue engineering in the reconstitution of implantable liver tissue.  
Methodology, K.F., M.S., M.D. and K.I.; Conceptualization, T.N. and Y.S.; investigation, M.L. and R.R.K.; Supervision, T.N., Y.S. and M.N. ([PERSON]); Methodology, M.N. ([PERSON]); writing and supervision, M.N. ([PERSON]); manuscript writing and final approval of manuscript, all authors. All authors have read and agreed to the published version of the manuscript.  
This research did not receive any specific grant from funding agencies in the public, commercial or not for profit sectors.  
Not applicable.  
The authors wish to thank [PERSON] for designing consultation.  
The authors declare no conflict of interest.