Naturally occurring IgG antibodies are bivalent and monospecific. Bispecific antibodies having binding specificities for two different antigens can be produced using recombinant technologies and are projected to have broad clinical applications. However, co-expression of multiple light and heavy chains often leads to contaminants and pose purification challenges. In this work, we have modified the CH3 domain interface of the antibody Fc region with selected mutations so that the engineered Fc proteins preferentially form heterodimers. These novel mutations create altered charge polarity across the Fc dimer interface such that coexpression of electrostatically matched Fc chains support favorable attractive interactions thereby promoting desired Fc heterodimer formation, whereas unfavorable repulsive charge interactions suppress unwanted Fc homodimer formation. This new Fc heterodimer format was used to produce bispecific single chain antibody fusions and monovalent IgGs with minimal homodimer contaminants. The strategy proposed here demonstrates the feasibility of robust production of novel Fc-based heterodimeric molecules and hence broadens the scope of bispecific molecules for therapeutic applications.

Hydrogels, consisting of hydrophilic polymers, can be used as films, scaffolds, nanoparticles and drug carriers. They are one of the hot research topics in material science and tissue engineering and are widely used in the field of biomedical and biological sciences. Researchers are seeking for a type of material that is similar to human tissues and can partially replace human tissues or organs. The hydrogel has brought possibility to solve this problem. It has good biocompatibility and biodegradability. After entering the body, it does not cause immune and toxic reactions. The degradation time can be controlled, and the degradation products are nontoxic and nonimmunogenic; the final metabolites can be excreted outside the body. Owing to the lack of blood vessels and poor migration ability of chondrocytes, the self-healing ability of damaged cartilage is limited. Tissue engineering has brought a new direction for the regeneration of cartilage. Drug carriers and scaffolds made of hydrogels are widely used in cartilage tissue engineering. The present review introduces the natural hydrogels, which are often used for cartilage tissue engineering with respect to synthesis, modification and application methods. The translational potential of this article This review introduces the natural hydrogels that are often used in cartilage tissue engineering with respect to synthesis, modification and application methods. Furthermore, the essential concepts and recent discoveries were demonstrated to illustrate the achievable goals and the current limitations. In addition, we propose the putative challenges and directions for the use of natural hydrogels in cartilage regeneration.

Background: Bispecific heterodimeric antibody consisting of two different heavy chains and two different light chains requires heterodimerization of heavy chains and cognate light-heavy chain pairings. Results: Cognate light-heavy chain pairing can be achieved by an antibody engineering approach. Conclusion: Bispecific hetero-IgG antibodies can be made in mammalian cells. Significance: The technology could be used in the production of bispecific antibodies for many biotechnological applications.

Obliterative bronchiolitis (OB) is the histopathological finding in chronic lung allograft rejection. Mounting evidence suggests that epithelial damage drives the development of airway fibrosis in OB. Tissue inhibitor of metalloproteinase (TIMP)-1 expression increases in lung allografts and is associated with the onset of allograft rejection. Furthermore, in a mouse model of OB, airway obliteration is reduced in TIMP-1-deficient mice. Matrilysin (matrix metallproteinase-7) is essential for airway epithelial repair and is required for the re-epithelialization of airway wounds by facilitating cell migration; therefore, the goal of this study was to determine whether TIMP-1 inhibits re-epithelialization through matrilysin. We found that TIMP-1 and matrilysin co-localized in the epithelium of human lungs with OB and both co-localized and co-immunoprecipitated in wounded primary airway epithelial cultures. TIMP-1-deficient cultures migrated faster, and epithelial cells spread to a greater extent compared with wild-type cultures. TIMP-1 also inhibited matrilysin-mediated cell migration and spreading in vitro. In vivo, TIMP-1 deficiency enhanced airway re-epithelialization after naphthalene injury. Furthermore, TIMP-1 and matrilysin co-localized in airway epithelial cells adjacent to the wound edge. Our data demonstrate that TIMP-1 interacts with matrix metalloproteinases and regulates matrilysin activity during airway epithelial repair. Furthermore, we speculate that TIMP-1 overexpression restricts airway re-epithelialization by inhibiting matrilysin activity, contributing to a stereotypic injury response that promotes airway fibrosis via bronchiole airway epithelial damage and obliteration. Bronchiolitis obliterans syndrome (BOS) is the manifestation of chronic lung rejection and limits the 5-year survival after lung transplant to less than 50%.1 In comparison, transplantations of other solid organs, such as the heart, pancreas, liver, and kidneys, have 5-year survival rates exceeding 70%.2 Obliterative bronchiolitis (OB) is the histopathological equivalent of BOS and is characterized by small airway fibrosis that contributes to progressive respiratory failure and death.3 Although the pathogenesis of OB is poorly understood, evidence suggests that the primary immunological target in the lung allograft is the airway epithelium. 4 -7 Moreover, aberrant airway re-epithelialization is apparently sufficient for the progression of fibrosis during the allograft rejection process. -13The airway epithelium is an important barrier in the innate defenses of the lung.14 After lung transplantation, persistent allo-dependent (eg, acute rejection) and alloindependent (eg, infection, ischemia) pressures on the airway epithelium necessitate rapid re-epithelialization to prevent further damage that can contribute to inflammation and fibrosis.3 Disturbances in the epithelial barrier are quickly repaired through coordinated processes by which epithelial cells bordering the injury quickly spread over the denuded basement membrane. [15][...

3D bioprinting is a promising strategy to develop heterogeneous constructs that mimic osteochondral tissue. However, conventional bioprinted hydrogels suffer from intrinsically weak mechanical strength, limited cell adaptability, and no sustained release of biochemical drugs, restraining their use as bioinks to emulate native osteochondral extra cellular matrix. Herein, a novel host-guest modulated dynamic hydrogel is developed for 3D bioprinting heterogeneous cell-laden constructs for osteochondral regeneration. Apart from gelatin methacryloyl (GelMA), this bioink consists of dopamine-functionalized GelMA and acrylate β-cyclodextrin and is crosslinked by host-guest interaction to develop the dynamic network for obtaining promoted cell adaptability, enhanced cell adhesion, reinforced mechanical strength, and tunable modulus. Moreover, based on the sustained drug release provided by the cavity of β-cyclodextrin, a heterogeneous construct is constructed by employing kartogenin (a chondrogenic factor) into the upper zone with lower Young's modulus and melatonin (an osteogenic factor) into the bottom zone with higher modulus to mimic the osteochondral microenvironment. With the favorable regeneration results in vitro and in vivo, a broad application of this bioink in 3D bioprinting for tissues engineering is expected.