Hypoxia Preconditioned Serum (HPS)-Hydrogel Can Accelerate Dermal Wound Healing in Mice—An In Vivo Pilot Study

Abstract

The ability to use the body’s resources to promote wound repair is increasingly becoming an interesting area of regenerative medicine research. Here, we tested the effect of topical application of blood-derived hypoxia preconditioned serum (HPS) on wound healing in a murine wound model. Alginate hydrogels loaded with two different HPS concentrations (10 and 40%) were applied topically on full-thickness wounds created on the back of immunocompromised mice. We achieved a significant dose-dependent wound area reduction after 5 days in HPS-treated groups compared with no treatment (NT). On average, both HPS-10% and HPS-40% -treated wounds healed 1.4 days faster than NT. Healed tissue samples were investigated on post-operative day 15 (POD 15) by immunohistology and showed an increase in lymphatic vessels (LYVE-1) up to 45% with HPS-40% application, while at this stage, vascularization (CD31) was comparable in the HPS-treated and NT groups. Furthermore, the expression of proliferation marker Ki67 was greater on POD 15 in the NT-group compared to HPS-treated groups, in accordance with the earlier completion of wound healing observed in the latter. Collagen deposition was similar in all groups, indicating lack of scar tissue hypertrophy as a result of HPS-hydrogel treatment. These findings show that topical HPS application is safe and can accelerate dermal wound healing in mice.

Hypoxia Preconditioned Serum (HPS) Promotes Osteoblast Proliferation, Migration and Matrix Deposition

“…Hypoxia preconditioned serum (HPS) is a new-generation blood-derived secretome that provides a therapeutic tool for bioactively supporting tissue repair by promoting angiogenesis/lymphangiogenesis, proliferation/migration of fibroblasts and dermal skin regeneration [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 34 ]. As the osteoblast can be considered a specialized fibroblast [ 43 ], we were intrigued about whether HPS has a similar impact on bone cells.…”

“…A deliberate choice was made for testing the HPS concentrations of 10% and 40% in this dose-dependent investigation of osteogenic and cytotoxic effects since we had previously established the safety and effectiveness of these concentrations in several in vitro angiogenesis/lymphangiogenesis assays, fibroblast migration experiments and more recently, in an in vivo murine dermal skin regeneration model [ 25 , 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. HPS dilutions are necessary to investigate the net effect of all growth factors in HPS since this depends on the balance of pro- and anti-angiogenic protein factors, the influence of the latter being diminished by dilution: Indeed, we had previously demonstrated greater angiogenesis with higher HPS dilutions [ 31 ].…”

“…Indeed, the current gold standard treatment of malunions by autologous bone grafting and mesenchymal stem cell therapy obtained from bone marrow aspirates partly relies on a multitude of biomolecules produced by the transplanted tissue [ 8 ]. Unlike these methods, which are burdened by donor site morbidity and high cost, we previously demonstrated the feasibility of using a simpler approach, specifically blood-derived secretomes, to promote tissue regeneration [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Peripheral blood cells (PBCs) are ideal providers of physiological regenerative signals which can be obtained on-demand using specific stress-induced treatment (e.g., hypoxia) [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ].…”

“…Unlike these methods, which are burdened by donor site morbidity and high cost, we previously demonstrated the feasibility of using a simpler approach, specifically blood-derived secretomes, to promote tissue regeneration [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Peripheral blood cells (PBCs) are ideal providers of physiological regenerative signals which can be obtained on-demand using specific stress-induced treatment (e.g., hypoxia) [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. In this context, we developed a novel method of extracorporeal hypoxia-adjusted in vitro preconditioning, which is based on incubating PBCs within a self-regulated low-oxygen microenvironment [ 23 , 24 , 25 , 29 ].…”

“…Indeed, we confirmed in several in vitro experiments that different processes involved in tissue regeneration, that is, angiogenesis/lymphangiogenesis, fibroblast proliferation and migration, can be promoted by HPS stimulation [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]—even under pathological conditions such as diabetes mellitus and cardiovascular disease treated with anticoagulant therapy [ 33 ]. Recently, we also successfully demonstrated the possibility of topically applying HPS via a hydrogel-carrier system to accelerate dermal wound healing in vivo [ 34 ].…”