Ageing of the population results in a number of age related diseases. Osteoarthritis/Osteoporoses, Invertebral Disk Disease and Renal fibroses are prominent age related diseases with hundreds of millions patients all over the world, in particular in the developed countries. Often the cure of these diseases is collectively called Tissue Repair. Tissue Repair is also required to heal wounds.
Growth factors [GF], in particular members of the TGFβ family, are playing a dominant role in Tissue Repair, however the effectivity of growth factors are limited as is well formulated by Martino in a Science (2014) paper: “GFs have been explored therapeutically, yet their translation to clinical use in regenerative medicine has been limited, probably in part because of their use at supraphysiological levels as well as issues related to safety and cost effectiveness”
Long before that paper Prof Karperien et al. at the University of Twente and the group of Prof Verrips at Utrecht University, worked out a strategy of controlled delivery of the growth factor (or an antagonist of such growth factor), by developing bi-specific VHH.
One of the VHH in the bi-specific VHH recognizes the (bio)material to be repaired. In figure 1 you see the visualization of Hydroxyl apaptite, an example of such a biomaterial.The other VHH of the bispecific VHH binds the growth factor.
The growth factors or their antagonists are: BMP 2, 4, 5, 6, 7; DKK and sclerostin, whereas the biomaterials that are recognized are: Hydroxy-apaptite; TiO, fibronectin, vitronectin and other EMC components.
An important aspect in Tissue Repair is measuring the repair process. QVQ has developed a number of VHH against markers of the repair process.