Biology subjects

Ponta, S.

Publications and source records attributed to Ponta, S..

5 recordsLinked to original sources

bioRxiv2026

Nose-to-Knee Transplantation for Osteochondral Regeneration: A Proof-of-Concept Study in Sheep Employing Ceramic-Hydrogel Osteochondral Grafts

Osteochondral defects remain a major clinical challenge, frequently progressing to osteoarthritis and ultimately requiring joint replacement. Despite advances in regenerative strategies, current approaches often fail to restore the structural and functional complexity of the osteochondral unit, resulting in poor integration and limited long-term performance. Here, we developed autologous osteochondral grafts combining mechanically mature nasal chondrocyte-derived cartilage with a 3D-printed strontium-hardystonite-gahnite trabecular bone scaffold, which was tested in an osteochondral defect model in sheep. Nasal chondrocytes were encapsulated in a hyaluronan transglutaminase-alginate hydrogel generating hyaline-like cartilage with physiologically relevant compressive properties (1.0 +/- 0.2 MPa) after 6 weeks of in vitro maturation. MicroCT scans of the osteochondral unit were used to design biomimetic trabecular bone scaffolds. Controlled infiltration of the hydrogel into the trabecular pores and subsequent cartilage maturation created a mechanical interlock between cartilage and bone layer, reaching an interfacial shear strength of 201 +/- 42 kPa. The translational potential of this approach was evaluated in a proof-of-concept ovine study. The engineered cartilage remained attached to the bone scaffold for three months following implantation, but osteochondral repair was limited by implant sinking, likely caused by inadequate implant fixation in the defect, resulting in micromotion, synovial fluid infiltration, osteolysis and subsequent bone cyst formation. Together, this work demonstrates the feasibility of engineering mechanically mature autologous osteochondral grafts while identifying subchondral bone integration as the primary bottleneck limiting successful osteochondral regeneration and future clinical translation.

bioengineering↗

bioRxiv2026

Benchmarking cartilage regeneration across ten chondrogenic cell sources using native tissue references

A persistent challenge in cartilage tissue engineering is identifying cell sources capable of regenerating cartilage with native-like properties. Variability in chondrogenic potential among human- and animal-derived cells complicates graft development and disease modeling. Here we benchmarked ten chondrogenic cell sources under standardized culture conditions using hyaluronan-alginate biomaterials and implementing a functionality index combining histological and mechanical metrics referenced to native tissue. Mesenchymal stem cells and fetal chondroprogenitors demonstrated superior regenerative capacity, achieving 103% and 95% of native cartilage functionality, respectively. In contrast, adult articular chondrocytes from healthy and osteoarthritic donors produced fibrocartilaginous tissue with functionality scores below 50%. These findings provide a quantitative framework to guide cell source selection and optimize cartilage graft standardization for clinical applications and physiologically relevant disease models, addressing regulatory demands for product characterization.

bioengineering↗

bioRxiv2026

Extracellular matrix context shapes morphogenesis and lactation-associated states in human milk-derived mammary organoids

The mammary gland relies on reciprocal interactions between epithelial cells and their surrounding extracellular matrix (ECM) to form and maintain milk-producing tissue structures. Yet these processes remain difficult to study in human model systems. Mammary epithelial cells (MECs) can be isolated noninvasively from breast milk, but whether they generate three-dimensional organoids and respond to matrix cues has been unclear. Here, human milk-derived MECs (milk MECs) spontaneously form complex organoids, including polarized acinar and terminal duct lobular unit-like structures after isolation. To investigate how matrix composition shapes these organoids, milk MECs were cultured in decellularized mammary ECM (dECM), Matrigel, and collagen I. In dECM, milk MECs formed polarized branched networks with aligned actin organization along collagen fibrils, whereas in Matrigel they adopted a more lactation-associated state, marked by {beta}-casein expression and milk fat globules. Together, these findings establish breast milk-derived MEC organoids as a human model to study how ECM context regulates mammary morphogenesis and lactation biology.

cell biology↗

bioRxiv2025

Tissue Engineered Elastic Cartilage-Mimetic Auricular Grafts for Ear Reconstruction

Patients born with microtia, the congenital malformation of the external ear, face substantial psychosocial strain. Current reconstruction relies on harvesting rib cartilage, an invasive procedure associated with donor site morbidity and unnaturally stiff ears due to the use of hyaline cartilage. Tissue engineered auricles could overcome these drawbacks by providing patient-specific elastic cartilage without the need for rib harvest. Yet, key challenges such as fibrocartilage formation, inhomogeneous extracellular matrix formation and mechanical inferiority during ex vivo maturation remain, often leading to graft deformation and degradation in vivo. To address this gap, we integrated approaches maintaining the chondrogenic potential with growth factors, promoting elastic cartilage formation through stress-relaxing materials, and achieving homogeneous maturation by culturing grafts on an elevated bioreactor platform that enables uniform nutrient diffusion, using primary human auricular chondrocytes. Together these approaches resulted in the maturation of bioprinted auricular grafts that closely resemble native human auricular cartilage, demonstrated by the uniform distribution of elastin, glycosaminoglycans, and collagen II, and lack of collagen I. RNA sequencing revealed gene expression patterns consistent with the transition from fibrocartilage towards elastic cartilage. On a functional level, grafts achieved a compressive modulus of 1.1{+/-}0.03 MPa, matching that of native human auricular cartilage (1.0{+/-}0.1 MPa) and maintained their structural integrity for 6 weeks in a subcutaneous rat model, where they transitioned towards mature elastic fibers. These grafts represent the closest approximation of native elastic cartilage achieved ex vivo to date, bringing the field closer to a clinically viable, long-term therapy for children affected by microtia. One-sentence summaryBioprinted auricular grafts develop native-like elastic cartilage and advance towards a durable therapy for children with microtia.

bioengineering↗

bioRxiv2022

Engineering of the Endogenous HBD promoter increases HbA2

The {beta}-hemoglobinopathies, such as sickle cell disease and {beta}-thalassemia, are one of the most common genetic diseases worldwide and are caused by mutations affecting the structure or production of {beta}-globin subunits in adult hemoglobin. Many gene editing efforts to treat the {beta}-hemoglobinopathies attempt to correct {beta}-globin mutations or increase {gamma}-globin for fetal hemoglobin production. {delta}-globin, the subunit of adult hemoglobin A2, has high homology to {beta}-globin and is already pan-cellularly expressed at low levels in adult red blood cells. However, upregulation of {delta}-globin is a relatively unexplored avenue to increase the amount of functional hemoglobin. Here, we use CRISPR-Cas9 to repair non-functional transcriptional elements in the endogenous promoter region of {delta}-globin to increase overall expression of adult hemoglobin 2 (HbA2). We find that insertion of a KLF1 site alone is insufficient to upregulate {delta}-globin. Instead, multiple transcription factor elements are necessary for robust upregulation of {delta}-globin from the endogenous locus. Promoter edited HUDEP-2 immortalized erythroid progenitor cells exhibit striking increases of HBD transcript, from less than 5% to over 20% of total {beta}-like globins. Edited CD34+ hematopoietic stem and progenitors (HSPCs) differentiated to primary human erythroblasts express up to 35% HBD. These findings add mechanistic insight to globin gene regulation and offer a new therapeutic avenue to treat {beta}-hemoglobinopathies.

genetics↗