Francesco Santarella

Diabetic foot ulcers (DFUs) are chronic wounds sustained by pathological fibroblasts and aberrant extracellular matrix (ECM). Porous collagen‐based scaffolds (CS) have shown clinical promise for treating DFUs but may benefit from functional enhancements. Our previous work showed fibroblasts differentiated from induced pluripotent stem cells are an effective source of new ECM mimicking fetal matrix, which notably promotes scar‐free healing. Likewise, functionalizing CS with this rejuvenated ECM shows potential for DFU healing. Herein, an approach to DFU healing is demonstrated for the first time using biopsied cells from DFU patients, reprogramming those cells, and functionalizing CS with patient‐specific ECM as a personalized acellular tissue‐engineered scaffold. A two‐pronged approach is taken: 1) direct ECM blending into scaffold fabrication, and 2) seeding scaffolds with reprogrammed fibroblasts for ECM deposition followed by decellularization. The decellularization approach reduces cell number requirements and maintains naturally deposited ECM proteins. Both approaches show enhanced ECM deposition from DFU fibroblasts. Decellularized scaffolds additionally enhance glycosaminoglycan deposition and subsequent vascularization. Finally, reprogrammed ECM scaffolds from patient‐matched DFU fibroblasts outperform those from healthy fibroblasts in several metrics, suggesting ECM is in fact able to redirect resident pathological fibroblasts in DFUs toward healing, and a patient‐specific ECM signature may be beneficial.

The most common three-dimensional (3D) printing method is material extrusion, where a pre-made filament is deposited layer-by-layer. In recent years, low-cost polycaprolactone (PCL) material has increasingly been used in 3D printing, exhibiting a sufficiently high quality for consideration in cranio-maxillofacial reconstructions. To increase osteoconductivity, prefabricated filaments for bone repair based on PCL can be supplemented with hydroxyapatite (HA). However, few reports on PCL/HA composite filaments for material extrusion applications have been documented. In this study, solvent-free fabrication for PCL/HA composite filaments (HA 0%, 5%, 10%, 15%, 20%, and 25% weight/weight PCL) was addressed, and parameters for scaffold fabrication in a desktop 3D printer were confirmed. Filaments and scaffold fabrication temperatures rose with increased HA content. The pore size and porosity of the six groups’ scaffolds were similar to each other, and all had highly interconnected structures. Six groups’ scaffolds were evaluated by measuring the compressive strength, elastic modulus, water contact angle, and morphology. A higher amount of HA increased surface roughness and hydrophilicity compared to PCL scaffolds. The increase in HA content improved the compressive strength and elastic modulus. The obtained data provide the basis for the biological evaluation and future clinical applications of PCL/HA material.

Collagen-glycosaminoglycan scaffolds are functionalized with alginate that responds to ultrasound by releasing nanoparticles on-demand for coordinated wound healing.

Diabetic foot ulcers (DFUs) are chronic wounds, with 20% of cases resulting in amputation, despite intervention. A recently approved tissue engineering product—a cell‐free collagen‐glycosaminoglycan (GAG) scaffold—demonstrates 50% success, motivating its functionalization with extracellular matrix (ECM). Induced pluripotent stem cell (iPSC) technology reprograms somatic cells into an embryonic‐like state. Recent findings describe how iPSCs‐derived fibroblasts (“post‐iPSF”) are proangiogenic, produce more ECM than their somatic precursors (“pre‐iPSF”), and their ECM has characteristics of foetal ECM (a wound regeneration advantage, as fetuses heal scar‐free). ECM production is 45% higher from post‐iPSF and has favorable components (e.g., Collagen I and III, and fibronectin). Herein, a freeze‐dried scaffold using ECM grown by post‐iPSF cells (Post‐iPSF Coll) is developed and tested vs precursors ECM‐activated scaffolds (Pre‐iPSF Coll). When seeded with healthy or DFU fibroblasts, both ECM‐derived scaffolds have more diverse ECM and more robust immune responses to cues. Post‐iPSF‐Coll had higher GAG, higher cell content, higher Vascular Endothelial Growth Factor (VEGF) in DFUs, and higher Interleukin‐1‐receptor antagonist (IL‐1ra) vs. pre‐iPSF Coll. This work constitutes the first step in exploiting ECM from iPSF for tissue engineering scaffolds.