The ALB gene encodes albumin, mainly produced in the liver, and is the most abundant protein in human plasma, accounting for 60% to 65% of total plasma protein. The proprotein encoded by ALB is processed to produce a functional protein, and the EPI-X4 peptide derived from this protein is an endogenous inhibitor of the CXCR4 chemokine receptor. Albumin plays a role in regulating plasma colloid osmotic pressure, helping to maintain blood circulation and isolating and transporting many metabolites within the body, especially insoluble hydrophobic metabolites ^[1]. Human Serum Albumin (HSA) is an important carrier protein involved in the transport of a variety of endogenous molecules, including hormones, fatty acids, and metabolic products, as well as exogenous drugs. As a natural carrier protein, HSA has multiple ligand binding sites and a plasma half-life of up to 19 days, making it a promising drug carrier. Several HSA-based drug delivery systems have been approved for clinical trials ^[2-3]. In addition, albumin is also the main transporter of zinc, calcium, and magnesium in plasma, binding approximately 80% of all plasma zinc and approximately 45% of circulating calcium and magnesium, with an affinity ranking of zinc > calcium > magnesium ^[4]. Diseases associated with the ALB gene include hyperthyroxinemia, familial serum albumin abnormality, and analbuminemia ^[5].

The ALPL gene encodes for the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme, a membrane-bound glycoprotein. This enzyme is expressed in a variety of cellular tissues, most notably in the liver, bone, and kidney, as well as in other areas like teeth and mesenchymal stem cells ^[6]. Its primary function is to act as a hydrolase, removing phosphate groups from molecules. This is a critical function for skeletal and dental mineralization, where it hydrolyzes inorganic pyrophosphate (a mineralization inhibitor) into phosphate, which then combines with calcium to form bone ^[7]. Mutations in the ALPL gene lead to hypophosphatasia (HPP), a rare inherited metabolic disease characterized by defective bone and tooth mineralization, rickets, osteomalacia, and in severe cases, seizures and respiratory complications. The severity of HPP varies, ranging from mild forms with dental issues to life-threatening perinatal forms ^[8]. Variations in the ALPL gene may also be associated with other diseases, such as osteoporosis. Research has found a high frequency of homozygous common ALPL gene variants in adult patients with atypical femoral fractures or with biochemical/clinical signs of hypophosphatasia (HPP). This suggests that variations in the ALPL gene may be linked to an increased risk of these fractures ^[9]. Furthermore, the expression and function of the ALPL gene may be relevant to cancer immunotherapy. Studies have shown that an alkaline phosphatase isoform, known as ALPL-1, is highly expressed in osteosarcoma (OS) ^[10].

B6-hALB/Alpl KO mice are generated by crossing B6-hALB (HSA) mice (Catalog No.: C001492) with Alpl KO mice (Catalog No.: C001849). Among them, Alpl KO mice are a gene knockout (KO) model: homozygous Alpl KO mice have a short lifespan, dying within 4 weeks even when fed with special feed; without special feed, no viable homozygous individuals can be obtained. This model can be used for research on the pathogenic mechanisms of diseases such as hypophosphatasia (HPP), osteoporosis, and osteosarcoma (OS), as well as for the development of therapeutic drugs using human serum albumin (HSA) as a carrier, and studies on in vivo efficacy and pharmacokinetics.