GAPDH suppresses adenovirus-induced oxidative stress and enables a superfast production of recombinant adenovirus

Dermal fibroblast-derived extracellular matrix (ECM) synergizes with keratinocytes in promoting re-epithelization and scarless healing of skin wounds: Towards optimized skin tissue engineering

Skin serves as the first-order protective barrier against the environment and any significant disruptions in skin integrity must be promptly restored. Despite significant advances in therapeutic strategies, effective management of large chronic skin wounds remains a clinical challenge. Dermal fibroblasts are the primary cell type responsible for remodeling the extracellular matrix (ECM) in wound healing. Here, we investigated whether ECM derived from exogenous fibroblasts, in combination with keratinocytes, promoted scarless cutaneous wound healing. To overcome the limited lifespan of primary dermal fibroblasts, we established reversibly immortalized mouse dermal fibroblasts (imDFs), which were non-tumorigenic, expressed dermal fibroblast markers, and were responsive to TGF-β1 stimulation. The decellularized ECM prepared from both imDFs and primary dermal fibroblasts shared similar expression profiles of extracellular matrix proteins and promoted the proliferation of keratinocyte (iKera) cells. The imDFs-derived ECM solicited no local immune response. While the ECM and to a lesser extent imDFs enhanced skin wound healing with excessive fibrosis, a combination of imDFs-derived ECM and iKera cells effectively promoted the re-epithelization and scarless healing of full-thickness skin wounds. These findings strongly suggest that dermal fibroblast-derived ECM, not fibroblasts themselves, may synergize with keratinocytes in regulating scarless healing and re-epithelialization of skin wounds. Given its low immunogenic nature, imDFs-derived ECM should be a valuable resource of skin-specific biomaterial for wound healing and skin tissue engineering.

An Intervertebral Disc (IVD) Regeneration Model Using Human Nucleus Pulposus Cells (iHNPCs) and Annulus Fibrosus Cells (iHAFCs)

Intervertebral disc (IVD) degeneration (IVDD), primarily caused by nucleus pulposus (NP) dehydration, leads to low back pain. While current treatments focus on symptom management or surgical intervention, tissue engineering using IVD-derived cells, biofactors, and scaffolds offers a promising regenerative approach. Here, human NP cells (NPCs) and annulus fibrosus cells (AFCs) are immortalized with human telomerase reverse transcriptase (hTERT), generating immortalized NPCs (iHNPCs) and AFCs (iHAFCs). These cells express NP and AF-specific markers, are reversible via FLP recombinase, and are non-tumorigenic. iHAFCs exhibit osteogenic potential, while iHNPCs show chondrogenic differentiation. A 3D-printed citrate-based scaffold was employed to develop an IVD regeneration model, with BMP9-stimulated iHAFCs in the peripheral region and BMP2-stimulated iHNPCs in the central region. Histological analysis revealed bone formation in the iHAFC region and cartilage formation in the iHNPC region, mimicking the natural IVD structure. Additionally, an ex vivo spine fusion model demonstrated robust bone formation in iHAFC-treated segments. These findings highlight the potential of iHAFCs and iHNPCs as valuable tools for IVD tissue engineering and regeneration.

Effective Bone Tissue Fabrication Using 3D-Printed Citrate-Based Nanocomposite Scaffolds Laden with BMP9-Stimulated Human Urine Stem Cells

Effective repair of large bone defects through bone tissue engineering (BTE) remains an unmet clinical challenge. Successful BTE requires optimal and synergistic interactions among biocompatible scaffolds, osteogenic factors, and osteoprogenitors to form a highly vascularized microenvironment for bone regeneration and osseointegration. We sought to develop a highly effective BTE system by using 3D printed citrate-based mPOC/hydroxyapatite (HA) composites laden with BMP9-stimulated human urine stem cells (USCs). Specifically, we synthesized and characterized methacrylate poly(1,8 octamethylene citrate) (mPOC), mixed it with 0%, 40% or 60% HA (i.e., mPOC-0HA, mPOC-40HA, or mPOC-60HA), and fabricated composite scaffold via micro-continuous liquid interface production (μCLIP). The 3D-printed mPOC-HA composite scaffolds were compatible with human USCs that exhibited high osteogenic activity in vitro upon BMP9 stimulation. Subcutaneous implantation of mPOC-HA scaffolds laden with BMP9-stimulated USCs revealed effective bone formation in all three types of mPOC-HA composite scaffolds. Histologic evaluation revealed that the mPOC-60HA composite scaffold yielded the most mature bone, resembling native bone tissue with extensive scaffold-osteointegration. Collectively, these findings demonstrate that the citrate-based mPOC-60HA composite, human urine stem cells, and the potent osteogenic factor BMP9 constitute a desirable triad for effective bone tissue engineering.

Establishment and characterization of a rat model of scalp-cranial composite defect for multilayered tissue engineering

Composite cranial defects have individual functional and aesthetic ramifications, as well as societal burden, while posing significant challenges for reconstructive surgeons. Single-stage composite reconstruction of these deformities entail complex surgeries that bear many short- and long-term risks and complications. Current research on composite scalp-cranial defects is sparse and one-dimensional, often focusing solely on bone or skin. Thus, there is an unmet need for a simple, clinically relevant composite defect model in rodents, where there is a challenge in averting healing of the skin component via secondary intention. By utilizing a customizable (3D-printed) wound obturator, the scalp wound can be rendered non-healing for a long period (more than 6 weeks), with the cranial defect patent. The wound obturator shows minimal biotoxicity and will not cause severe endocranium-granulation adhesion. This composite defect model effectively slowed the scalp healing process and preserved the cranial defect, embodying the characteristics of a "chronic composite defect". In parallel, an autologous reconstruction model was established as the positive control. This positive control exhibited reproducible healing of the skin within 3 weeks with variable degrees of osseointegration, consistent with clinical practice. Both models provide a stable platform for subsequent research not only for composite tissue engineering and scaffold design but also for mechanistic studies of composite tissue healing.