Life science
Medical & healthcare, Tissue engineering, Regenerative medecine

Injectable prevascularized mature adipose tissues (iPAT)
to achieve long-term survival in soft tissue regeneration
Joint Research Laboratory (TOPPAN) for Advanced Cell Regulatory Chemistry, Graduate School of Engineering
Specially Appointed Assistant Professor Fiona Louishttps://researchmap.jp/fiona-louis?lang=en

Life science

Abstract
The study introduces a method for enhancing soft tissue regeneration using injectable prevascularized mature adipose tissues(iPAT). It involves culturing mature adipocytes, adipose-derived
stem cells, and endothelial cells from patients, embedded in fibrin
gel with collagen microfibers. The iPATs are injected into mice forup to 12 weeks, showing promising results in thriving and integrating effectively. The prevascularization helps nutrient and oxygen
supply, enhancing their integration with surrounding tissue. This
research holds promise for medical applications like breast reconstruction, wound healing, and tissue repair.

▍ Background & Results
Adipose tissue regeneration is crucial for various medical applications, including cosmetic surgery, post-tumor resection, andtrauma treatment. Current methods, like fat reinjection from liposuction, face challenges such as graft resorption and volume loss
due to inadequate vascular support. To address these issues,
we developed collagen microfiber tissues that can guide blood
vasculature development while protecting mature adipocytes. The
created injectable prevascularized mature adipose tissues (iPAT)
mix mature adipocytes, adipose-derived stem cells (ADSCs), andendothelial cells (HUVEC) from patients, embedded in a fibrin gelwith the collagen microfibers.

The iPAT balls were cultured with high viability, maintaining themature adipocytes unilocular lipid vesicle phenotype. Co-culture
with ADSCs and HUVEC allowed for a dense vasculature similar
to in vivo conditions, allowing fluid diffusion for nutrient transport.
After injection, iPAT balls can merge into a bigger size tissue insubcutaneous. Compared to non-vascularized adipose balls andliposuctioned adipose tissues, iPAT showed higher graft retention,
fewer fibrotic areas, and superior cell survival after 1 and 3 monthsof implantation in mice. RNA-sequencing analysis also revealed
upregulated angiogenesis-related genes. Additionally, lymphatic
and neural networks were observed in iPAT, indicating a potential
mechanism for tissue survival. Finally, rheological analysis showedthat iPAT grafts exhibited elastic behavior similar to in vivo adipose
tissue, and cryopreservation possibility was confirmed, allowing for
future reinjections.

▍ Significance of the research and Future perspective
These findings suggest that iPAT may offer a promising solution
for adipose tissue transplantation with improved graft retention,
angiogenesis, and cryopreservation capabilities, making it a valuable option for various clinical applications with customized implantvolumes.
Future research will now focus on longer-term studies, in bigger
size animals, and scaling up the process.

P a t e n t JP2023101792A, WO2022091822A1, JP2021145677A
Louis, Fiona; Sowa, Yoshihiro; Irie, Shinji et al. Injectable prevascularized mature adipose tissues (iPAT) to achieve long‐term survival in soft tissue
regeneration. Advanced Healthcare Materials 2022, 11(23), e2201440. doi: 10.1002/adhm.202201440
Louis, Fiona; Sowa, Yoshihiro; Kitano, Shiro et al. High-throughput drug screening models of mature adipose tissues which replicate the physiology ofpatients’ Body Mass Index (BMI). Bioactive Materials 2022, 7, 227-241. doi: 10.1016/j.bioactmat.2021.05.020
Tr e a t i s eLouis, Fiona; Piantino, Marie; Liu, Hao et al. Bioprinted vascularized mature adipose tissue with collagen microfibers for soft tissue regeneration. Cyborgand Bionic Systems 2021, 1412542. doi: 10.34133/2021/1412542
Louis, Fiona; Kitano, Shiro; Mano, João F et al. 3D collagen microfibers stimulate the functionality of preadipocytes and maintain the phenotype of matureadipocytes for long term cultures. Acta Biomaterialia 2019, 84, 194-207. doi: 10.1016/j.actbio.2018.11.048
URL http://www.chem.eng.osaka-u.ac.jp/~matsusaki-lab/
K e y w o r d adipose tissue, vascularization, tissue engineering, breast reconstruction