INTRODUCTION

Many toothaches are the result of chronic bacterial infections that cause inflammation of the connective, vascular, lymphatic and nervous tissues occupying a chamber in the center of the tooth. When these tissues, collectively referred to as the pulp, become chronically inflamed they must be removed in a procedure known as a root canal treatment. Even when bacterial infections do not penetrate into the pulp chamber, a root canal may be required because bacterial by-products can diffuse through the remaining tooth structure and cause chronic pulp inflammation. In an effort to treat these conditions, a century's old procedure called pulp capping is often employed, which consists of placing a material such as calcium hydroxide on the remaining tooth structure that creates a high pH, antimicrobial environment.

Tooth sensitivity affects millions of people and can be traced to an inadequate amount of dentin insulating the pulp cavity. Normally, dentin is insulated by enamel on the crown of the tooth, and by gum tissue on the roots of the teeth. Tooth sensitivity can occur when these insulators deteriorate. For example, tooth sensitivity can arise because of a deep cavity, a deep dental restoration (e.g., amalgam, composite, a crown, etc.), periodontal disease, or because of aging.

One goal of regenerative dental medicine is to stimulate the generation of dentin (e.g., from odontoblasts) with the same structural and biological properties of native dentin. In doing so, the vitality and function of the existing teeth can be preserved. Odontoblasts secrete an extracellular matrix that undergoes mineralization and are trapped within the pulp chamber. Unless the pulp cavity has been exposed, delivery of medicants (e.g., therapeutic agents) to pulpal tissues is difficult. The pulp is surrounded by dentin, a mineralized matrix that protects the pulp cavity from thermal, chemical and other noxious stimuli. The only means to access the pulp is either through mechanical exposure (drilling) or delivery of the medicant via the dentinal tubules. Dentinal tubules are small (2.5 μm diameter), fluid filled cannuli that house the odontoblastic process.

The present disclosure provides compositions and methods for delivering lipophilic agents to pulp tissue, and/or for enhancing dentin production by dental pulp tissue (e.g., in the context of pulp exposure, tooth sensitivity, and the like).

PUBLICATIONS

Han et al., PLoS One. 2014 Feb. 10; 9(2):e88890; Yang and Liu, Stem Cells In Oral Medicine. 2012; 1(1): 3-8; Arioka et al., Biochem Pharmacol. 2014 Aug. 15; 90(4):397-405; Biomaterials. 2015 January; 39:145-54, Epub 2014 Nov. 22; Thesleff and Tummers, StemBook [Internet]. Cambridge (Mass.): Harvard Stem Cell Institute; 2008-2009 Jan. 31; Minear et al., Sci Transl Med. 2010 Apr. 28; 2(29):29ra30; Westendorf et al., Gene. 2004 Oct. 27; 341:19-39; Moon et. al., Nat Rev Genet. 2004 September; 5(9):691-701; Dhamdhere et al., PLoS One. 2014 Jan. 6; 9(1):e83650; Zhao et al., Methods Enzymol. 2009; 465:331-47; U.S. patent publication numbers: 20140371151, 20120115788, 20120329790, 20120231091, and 20080226707; PCT publication number WO2012122081; and U.S. Pat. No. 8,809,272.

SUMMARY

Methods and compositions are provided for enhancing dentin production, and for delivering a lipophilic agent to pulp tissue of a tooth of an individual. In some embodiments, a subject method includes a step of administering to the pulp of a tooth of an individual, a Wnt stimulating composition that includes a Wnt stimulator agent, at a dose sufficient to enhance the production of dentin by the pulp. In some cases, the pulp is exposed pulp and the administering step includes contacting the exposed pulp with the Wnt stimulating composition. In some cases, the administering step includes a step of contacting dentin with the Wnt stimulating composition, whereby the Wnt stimulating composition penetrates the dentin to the underlying pulp tissue. In some cases, the Wnt stimulating composition includes a lipophilic Wnt stimulator agent inserted in the non-aqueous phase of a lipid structure. In some such cases, the lipophilic Wnt stimulator agent is a Wnt protein (e.g., a Wnt protein having a lipid moiety). In some cases, the Wnt protein is Wnt3A (e.g., human Wnt3A). Thus, in some cases, the Wnt stimulating composition includes a liposomal Wnt (L-Wnt), e.g., liposomal Wnt3A (L-Wnt3A).

In some embodiments, a subject method includes a step of contacting exposed dentin of a tooth with a composition that includes a lipophilic agent inserted in the non-aqueous phase of a lipid structure (e.g., whereby the lipophilic agent penetrates the dentin to the underlying pulp tissue). In some cases, the individual has tooth sensitivity or is at risk of developing tooth sensitivity (e.g., following a dental procedure). In some cases, the pulp of the tooth is exposed and in some cases, the pulp of the tooth is not exposed. In some cases, a subject method includes, prior to the contacting step, a step of exposing dentin of the tooth. In some cases, the lipophilic agent is a growth factor having a lipid moiety. In some cases, the lipophilic agent is a Wnt stimulator agent having a lipid moiety. In some such cases, the Wnt stimulator agent is a Wnt protein (e.g., a Wnt protein having a lipid moiety). In some cases, the Wnt protein is Wnt3A (e.g., human Wnt3A). Thus, in some cases, the lipophilic agent inserted in the non-aqueous phase of a lipid structure is a liposomal Wnt (L-Wnt), e.g., liposomal Wnt3A (L-Wnt3A).

In some cases, a Wnt3A protein is delivered to the pulp cavity. The lipophilic WNT3A protein can be tethered to a lipid vesicle, which can stabilize the in vivo biological activity of the protein. The liposomal Wnt3A (L-Wnt3A) formulation can be applied to exposed dentin, whereby the liposomal particles penetrate the dentin through the dentinal tubules, which extend from the outside of the tooth to the pulp cavity. There, L-Wnt3A can enhance both the survival and proliferation of pulp cells, and can stimulate the formation of dentin (e.g., tertiary dentin), which insulates the tooth and protects the pulp from thermal and chemical insult. By stimulating new dentin formation, the risk of bacterial infection of the pulp and overall tooth sensitivity are reduced and the need for root canal therapies, extensive prosthetic replacements, and tooth extraction are reduced. The subject methods can augment the body's natural response to tooth sensitivity: topical application of a liposomal protein therapeutic can stimulate dental pulp cells to produce more dentin and in doing so, provide additional insulation to the teeth. The subject methods have broad applications in general restorative dentistry, prosthodontics, and periodontics. Kits are provided for practicing the methods of the disclosure.

