Customizable and Open-Source 3D Printed Inserts for Controlled Release and Cell Culture Experiments

Cell culture inserts are a key tool
for in vitro experimentation
in both cell-based assays and general in vitro analytical experiments.
However, during and following the COVID-19 pandemic, a combination
of increased demand and disruptions to global supply chains saw massive
reductions in their availability. Many researchers faced long lead
times and experienced significant research delays as a result. In
addition, the high cost and limited customizability of commercial
inserts make them inaccessible to researchers with limited funding
resources and inappropriate for specialized research applications,
respectively. We sought to develop a low-cost, open-source, and customizable
3D printed insert platform to address these issues of availability,
accessibility, and customizability. Hanging-type 3D printed inserts
(3DPIs) were designed as two componentsthe insert cradle and
the donor welland assembled into a complete insert following
3D printing via fused-filament fabrication. The performance and versatility
of the 3DPIs were demonstrated through a series of exemplar in vitro
experiments. In a conventional permeability assay, 3DPIs supported
cell monolayer formation and successfully restricted large molecule
transport. In a T cell migration assay using a hydrogel biomaterial,
3DPIs (20 μm pore size) enabled evaluation of the cell encapsulation
and release properties of the biomaterial. Finally, solvent-resistant
3DPIs were used to develop a drug diffusion assay for an in situ forming
implant formulation. The 3DPIs exhibited comparable performance to
commercial inserts when conducting the permeability assay. However,
only the 3DPIs could be used in the cell migration and drug diffusion
assays due to the limited range of membrane pore sizes offered by
commercial inserts (≤8 μm) and their poor solvent resistance.
The 3DPIs could be easily customized to serve the requirements of
the target experiments. Importantly, due to the use of open-source
hardware and software, the 3DPIs could be locally manufactured at
extremely low cost. As a result, the 3DPIs invariably have greater
accessibility and improved availability, which could make their use
more resistant to funding challenges, or supply chain disruptions,
and provide a viable alternative to commercial cell culture inserts.